Ok, I take back what I said on Page 41.
This post should be really helpful for people just starting out because the game is pretty garbage about telling you what everything does especially down deep in the skill trees.
I got a little obsessive compulsive about the various build options because respecs are few and far between and I didn't want to end up with a gimp. So I fought probably a hundred battles in the arena total. I saved right before the fights and then used the respec gem to test out builds.
Here is what I found, YMMV. All these builds were using roughly equal damage gear and armor BTW.
Magic doesn't suck. In the beginning like many many RPGs its a little dodgy and weak primarily because mana is a resource and running out sucks. There is no equivalent stamina bar for melee attacks so you don't run out of 'ammo'.
The 5 basic skill trees basically break down like this:
Blades- Melee multi target weapon. Brutal damage on unarmored opponents, has a sweep attack that gets progressively better. I see no compelling reason to use one handed weapons in this game. They are marginally faster but don't hit nearly as hard and you can't use an off hand weapon or shield. This goes for blunt too.
Blunt- Single target damage king. These weapons hit hard as fuck but are much slower however you needn't strike many times to down someone. They also destroy armor and have big knockdown effect. They mostly are single target however until they very end of the skill tree.
Guns- Very powerful early game, but they level out quickly against the other skills once you have a few levels under your belt. The ranged thing is an obvious advantage but you aren't terribly maneuverable especially with long guns. Pistols suit a quicker play style of course and shoot faster so you can be more mobile. I was also wrong about Anointed weapons working on ranged weapons. Bizarrely the anointed weapons skill tree is buried behind the firearms tree, wtf? Spiders I guess... *shrug*
Traps- I didn't max this tree but it is underwhelming because the area of effect radius is pretty small. Likewise, the same exact things you use to anoint weapons also are used for traps so you are better off just putting that elemental trap on a weapon instead of on the ground. Related, bombs are ok, but an anointed two handed sword was hitting for WAY more damage in the sweep attack then a single bomb could do, because the bomb has a cooldown whereas you can swing the blade around over and over and are applying elemental, stasis, DoT poison, etc to every monster you hit. Nasty shit.
Spells- I take back what I said completely. With a good divine ring and a fully spec'd mage you are an engine of death. Their big "spell" powers aren't great, I stand by that. The PBAOE power is very decent because it has damage and knockdown. (The one dead center bottom of skill tree between Spells / Traps), but the others are pretty lame. But both the magic attacks the shadow bolt and even the melee attack get retardedly powerful if you go deep into the tree. And remember, you TOTALLY ignore armor. So its crazy fucking OP actually when you are firing up guys in heavy plate like they are wearing tissue paper.
With the 'Dishonored' blink power and an unlocked Divine skill line you also get a really fast blink attack and strike off your secondary attack. So what happens is you basically become Nightcrawler. My dude was teleporting around between like 3-5 guys and massacring. I'd use the teleport strike to hit and then immediately blink out w/ the evasion blink. Then again, lather rinse repeat. The shadow bolt I'd throw at targets I wasn't in blink range of. Ugliness ensued. You really need to focus on magic damage ability and magic points ability to make this work though so your other skills will suffer for it. Price you pay to play an X-Man!