OFFENSE TREE.
Sundering Strikes.
Not much to say here - it's a nice, reasonably small bonus, which main function for now, as i see it, is to bring certain weapons (mostly low-mid tier ones) from that uncomfortable "less than 100% effectiveness against armor" state. In addition, there ain't much competition in the first tier (which is a reocurring issue), so, in most cases, if a character goes into the Offense tree at all, he will most likely take this. If there's one issue with that skill, it's that it certainly works, but it's effect is not immediately apparent - there's no distinctly new tactical possibility that it might open, it's just there, working. Of note, however, is, if my suspicion regarding how "weapon durability versus armor" works is correct, this skill might improve the chances of your equipment surviving an engagement with armored enemies. Or i might be completely wrong.
Crusher.
There's already a decently done number-crunching on official forums regarding various type of shield-splitting weapons versus various types of shields so I won't repeat it here, but what it all boils down to is: shields we have in the game now can be split (pun maybe not intended) in two categories - the ones that are perfectly breakable without that perk, and the ones that are so tough you'd better bypass them, rather than break them. Thing is, as far as action economy goes, you don't want to spend more than two attacks on breaking a shield, and ideally you spend one. Those may be spread among multiple characters. On paper, you can surround one enemy combatant with six of yours, so you'd have plenty of breathing space to take down his shield and have attacks left to spare to take down him. In practice, with how conscious AI is of positioning and how you yourself want, most of the times, to maintain a proper formation, you will only engage one enemy combatant with two, three tops, of yours, unless it's a "pile on the last dangerous enemy" situation. And in that case, you either make one of your characters use a weapon that can break that shield without that perk(Quick Hands Two Handed Ax From The Backpack Surprise Attack!), or make peace with the fact that you'll need two+ turns to get through that shield. In conclusion, Crusher is kinda bad, some numbers might need to be tweaked, or new items with wider range of "shield hp" and "shield damage" introduced, to make it worthwhile. Currently it only serves to give a teensy boost to hatchets, which will get replaced at first opportunity with more capable weapons, so it's a waste.
Bloody Harvest.
Kinda like with Sundering Strike - if a character is going into the Offense Tree and intends to use a weapon with an AoE attack, that character takes this. Otherwise he does not. A worryingly binary choice. There might be some borderline cases, where you'd make a character focused on using the primary attack of an aoe-capable weapon and don't bother with the secondary, but that's woefully suboptimal - why not use the Billhook instead? I am sure this will sort itself out when we see equipment roster expanded, and there will emerge a wider range of possible weapon specializations, so not an issue, I hope.
Executioner.
As it is now, this serves to fuel "on-kill" abilities of characters with multiple attacks, to make really really sure they'll trigger. Otherwise it's lackluster - if you're already damaging enemy HP, and not armor, there's almost no doubt he will go down quickly unless you're poking him with kitchen knives. To boot, if you're damaging enemy HP, but he has sufficient HP to survive multiple attacks, he will most likely fail a morale check and start fleeing, which in (absolute) most cases will allow you to kill him, with no AP cost, on his turn. If there's going to be an enemy with little armor, a gargantuan amount of hitpoints and some steely Resolve, it might be maybe perhaps worth it to spend a skill point to deal with that enemy in particular, because that sounds problematic. Maybe if, instead of a +20% bonus to damage, Executioner provided a +10% to hit and +10% to damage, for example, it would become more attractive and, in addition would reinforce the general skill tree dynamic (other first tier talents in Offense tree either provide a to-hit bonus somehow, or otherwise serve to give an edge to beginner characters).
Push The Advantage.
Headshots are a mixed blessing. On one hand, if you already dealt with enemy headgear, or he wasn't wearing one, it's almost guaranteed instakill. On the other hand, you might've already dealt with the enemy body armor, but he still has a helmet, and instead of dying he's now going to wreck you for ruining his shirt. Which is especially pronounced in the early game with Bandit Raiders, who have relatively weak body armor(maximum a basic chain shirt), but at the same time have one of, if not the toughest mid-range helmets in the game. So there's that. Otherwise, some interesting team-play synergies can be built with that skill, some mace wielders and/or masters of the Defense tree and some high damage weapons with bonuses to hit the head. Basically, that's what I like to see, a skill that has the capacity to change the way you arrange formation, choose equipment and plan complex synergies, both contained within a single build, and across multiple characters.
Fast Adaption.
This is the worst offender in the Offense tree first tier, competition-wise. Regardless of weapon of choice, or overall build, be it melee or ranged, two-handed or one-handed, a character going into the Offense tree will take this. That's not even an option – doing otherwise makes no sense. And by itself, that's not a bad thing – it's nice to have a reliable, constantly useful skill. The issue is in that no other skill in that tier provides a benefit of comparable magnitude or reliability.
First tier conclusion.
Almost no competition for skill points. There is a limited number of choices which strictly dictate which skills you'd take from that tier, which leads to kinda standardized, cookie-cutter picks. The only possible deviation from those is Push The Advantage, which requires either planning for very high-level, or a team-build – not bad by itself, but that's just one option. I do really hope for some tweaks that will allow for more varied offensive specialists and/or make those skills viable for the entire progression of a game, not just on low level.
Berserk.
I don't think the name is appropriate. Otherwise, this is good, and becomes better the higher level the character is(provided you level up Fatigue). 4 AP is two tiles of movement, or raising a Shield Wall, or making another attack(even with a two-hander, provided you didn't move) – wide range of both offensive and defensive applications, can serve both two-handed and one-handed builds, and even archers(to a lesser extent). Almost no reason not to pick it and, as I think I've already established, that is an issue.
Head Hunter.
Same things i’ve said about Push The Advantage apply here – headshots can either really really help you, or really really hinder you. The erratic nature of this skill's operation confounds the issue further – making this skill undesirable for any character that's not specifically built to be a head hunter. And that's great, actually. A proper, specialization-defining skill, in some circumstances(having the right weapon, applying the right status effects) can raise your to-hit-the-head-chance as high as 70-80% really fast. What kinda bothers me is – how does it function in combination with a two-handed ax basic attack, which, supposedly, hits both the head and the body? Say, it hits the head first(resetting any possible bonus you might've had from this skill), then it hits the body(giving you a bonus) - will the next attack, an AoE one, for example, have that bonus? Or am I reading all this completely wrong?
Full Force.
I have no issue with that one. Some numbers and bits: you can get up to +32 maximum damage from that skill, by wearing a Heraldic Mail and, if I am reading this right, that number will gradually deteriorate during combat, as the armor gets damaged and the skill states it takes only the current body protection into account. That's a tactical and strategic consideration to be made here – do you give this to a shield-bearer with a somewhat lighter armor, and enjoy a limited, but safe and reliable bonus to damage? Or do you stick it onto a two-handed juggernaut and send him wading in, hoping to score those high damage hits before his armor is stripped? Or you keep him In reserve behind a formation, waiting to unleash his full potential when the right moment comes? This is good.
Debilitate.
This is bad. The idea itself is nice, and I can see it being reincarnated in Utility tree(or Support tree, more on that later) as some form of order, like, “Men, TAKE DOWN THAT ONE!”. How it functions now, however, is just awful. On paper it seems attractive, but then you realize that it costs as much AP and fatigue as an attack, deals no damage, has a chance to miss, and that's just all over the place. To fix/improve that, the effect of this skill should be tied to the weapon the character is using, and be a honest, proper attack, with a penalty to hit and increased stamina cost, but dealing weapon damage and taking into account all of weapon qualities – “+% chance to hit the head”, increased reach, being ranged even, and so on. Basically, you aim for something vital and important and attempt to hit that. In addition, I think that so crippled target should become easier to hit(maybe a flat +10% or +15% increase to to-hit chance). That is, I propose breaking this skill into two skills. One, a battle order type of affair, would depend on Resolve of a character using it, have 5 tiles range(standard for resolve-dependent abilities, I believe) and give a considerable (like 30-40% of character's Resolve as bonus damage) benefit. The other, a specialized attack, should depend on Ranged or Melee Skill of the character using it, be in all aspects tied to the qualities of the weapon used to perform it, have a penalty to hit chance, and provide a (small) flat, but stackable, bonus to further damage and to-hit chance.
In addition, just as an aside – with current range of weapon damage and the size of characters(and monsters) HP pools, bonus damage is only good up to a point, and that point is not hard to reach, and after that you're just over killing. This, in itself, is good and gives combat a realistic feel, but that's something to be taken into account when picking up combat abilities.
Bullseye.
I think this should be a tier one skill. In the beginning, ranged-type characters are somewhat weak, miss often and are awkward to use and position. Placing this into tier one would introduce a trans-tree choice – you either take this and can now keep archers within formation with more safety, or you take Pathfinder to make it easier(but still risky) to position them for flanking attacks with no line of sight interference. Other than that, it's reliable, comes in use often and I, generally, don't believe in ranged characters not taking it(and that's both good and bad).
Close Combat Archer.
Completely worthless for multiple reasons. First one is Quick Hands, a tier one skill from another tree (that is to say, taking it will not preclude you from reaching mastery ability in the Offense tree). If there's an enemy within 2 tiles of your archer, there are two possibilities – he's either behind your shield wall, in which case you should switch to a billhook and hit him on the head without any penalties to hit resulting (even reduced by Bullseye) from interrupted line of sight; or there's no one around to cover your archer, in which case he should run away, not shoot. To boot, the damage of melee weapons is universally higher than ranged ones, and those +50% don't close the gap. If that skill gave increased to-hit or to-hit-the-head chance, or increased armor damage, or an ability to bypass shields, basically, something else, it might be worthwhile. As it is now, it's opportunity cost is too high for a rather pointless benefit it provides.
Second tier conclusion.
Again, almost no competition. Of the 6 skills, 2 are useful for all characters, one for melee and one for ranged. In the race for the mastery ability, that allows for a bit more variance than in the first tier(you can take 3 skills from first tier, but you only need 2 from the second tier to reach mastery), but still not enough.
Perfect Focus.
Let me quote something you wrote in your FAQ
. “Battle Brothers will always be common humans in a pseudo-medieval setting that sometimes have to go up against non-human and supernatural foes. It is for this reason also that we try to avoid skills for the player that feel clearly unrealistic and superpowery (e.g. shooting 3 arrows at once) to keep things grounded a bit.”
I think it's clear where i'm getting with this, but still – it seems you got carried away a bit. This skill, even by itself, when not supported by other abilities and characters, is borderline overpowered. You can shoot three(actually closer to five or six) arrows at once. You can swing ALL THE BILLHOOKS. You can reload and shoot two crossbows. Yes, you won't be doing much for the next two to three turns and that kinda balances it out. The issue is raised when that skill gets supported by Battle Flow(requiring 11 level character) or by Rally The Troops(requiring one 6 level character supported by one or two other 6 level characters). There's no combination of enemy units that can stand up to this currently. There are no enemies that can break or avoid that combo. It's an I Win button. Up until now I advocated buffing up lackluster abilities to be on par with the good ones, instead of nerfing the good ones(which, I believe, is the proper way to design and tune rule-sets, not the other way around), but this needs to be toned down. Yes, it requires considerable effort and preparation, it dictates how your formation functions, it loses some(not all) effectiveness if your horn-blowers get wasted, and it does provide a feel of well-oiled combat machine, a functioning formation. I actually like it, but I confess that I like it too much.
Killing Frenzy.
The main falling of that skill is in that it's nowhere near Perfect Focus. There are others, that make it less consistently useful – the AI is clever and tries to avoid frenzied characters, it provides yet another bonus to damage(+50%, compared to Perfect Focus' +300-500%) to individual attacks, which makes you overkill more. But overall, it's a solid ability, AoE-capable characters can get considerable use out of it and it would see more use, if only it weren't so completely overshadowed by it's neighbor.
Offense tree conclusion.
Characters going all-in into the Offense tree are going for Perfect Focus. That path is disappointingly straight-forward and allows for little variation, there's basically no pondering – “what should I take?”, “can I customize that merc to be characteristic and unique, but no less effective than that other one with the same weapon?”. There are AoE-dispensers, archers and an occasional billman and that's pretty much all. I feel that I kinda sound harsher than I mean to, justifications can be made to point out that, yes, knights, skirmishers and billmen were, in fact, the main “unit-types” of that period of warfare, for example. But in the game, I think we can do with more variety and CO shenanigans.
In general, one of the biggest problems with the skills as they are is that for a lot of the them it is obvious whether or not you would want to take them. If you don't want your merc to use an axe, not taking Crusher is already a no-brainer and if you are not using AoE, Bloody Harvest is a no-brainer, and so on. In essence, there are a lot more phantom choices than real choices here. Skills like Fast Adaptation that are applicable across a lot of character types is the best way to go.