1. Is it me or is two weapon fighting superior to other setups? Especially for Fighters and Gladiators, with their Oversized two weapon fighting feat (Mantises too). The ability to use two handed weapons in one hands make two handers used "solo" very weak. Right?
2. How does fighting with 4 weapons work for a Mantis? One weapon is the main but what about three others? Can one have additional attacks from the improved/greater/perfect two weapon fighting feats? Would it mean (with belt of full BAB and Oversized feat) 4 (main hand) + 4 (left) +2 (from weapons in additional hands) = 10 attacks with one handed weapon? 7 of them at full attack bonus. In theory at least.
It depends of your build and how many feats you can spare, mostly, original (=maximal) difficulty doesn't give a lot of feats, even if Fighters get plenty, there's a lot of good feats and some defensive ones like saving throws, against paralysis, improve stand/rearm or improve resistance to paralysis/death, even die hard might save you some tears.
Then, there's improve/greater trip, grapple and the likes, even when you don't use them too much, it works defensively as well...
And then the crit related, attack, cleave, reflex, armor related...
That's a shitload of good feats, on highest difficulty, you have to make some choices.
Also, keep in mind using 4 weapons is great but most of the game, you'll be using one great + 3 crap weapons or at least 3 average weapons.
Is it not better to save feats and focus on crafting one great weapon instead?
I've played a Mantis Gladiator with oversized and 4 weapons, last two weapons were useless, mostly, except for going through mirror images or for the buffs they gave, like that +2 STR axe.
As for the number of attacks, yes, you get a lot of them, I can't remember exactly if your numbers are correct but sure, it feels good.
Except with a skewer weapon and greater cleave, your main/2nd weapon do the job by themselves and when fighting a resilient enemy, 3rd and 4th weapon don't add much anyway, you'll only see the difference if you have 4 identical crap weapon.
And you don't have the resources to craft 6 great weapons 4 for your mantis and 2 for your second fighter, not even counting other hybrids you might have.
As for the third question, I don't use that rule but I'm sure it's probably harder to implement as you would have to keep track of every character HP before each combat as well.
And looking at the negative reviews, I don't think it'd be received very well either, just don't use it or keep it at 5%.
Edit:
It'd be different for a rogue Mantis, because by mid game, there's plenty of light weapons nobody is going to use and many status effects will give you sneak attack opportunities so you don't need great secondary weapons.
