I'm running a game, and house ruled that the Double Slice feat give the full power attack bonus along with the full strength bonus for the offhand. I thought I was being clever, but a quick search on the boards let me know that I wasn't the first with that idea. Despite the minor blow to my ego, this actually works in my favor as I can ask all you homebrew guys and gals if you've done this, and how it worked out?
For clarificaiton my custom feat reads:
Your off-hand weapon while dual-wielding strikes with greater power.
Prerequisite: Dex 15, Two-Weapon Fighting.
Benefit: Add your Strength bonus to damage rolls made with your off-hand weapon. Additionally, if you have the power attack feat, you may remove the -50% damage penalty for attacking with an off-hand weapon.
Normal: You normally add only half of your Strength modifier to damage rolls made with a weapon wielded in your off-hand. You only add half of your power attack damage to power attacks made with your off-hand.
Its not a major issue Its hard for TWF to get off full attacks so it comes up a lot less.
Really the extra damage is gonna add up but not really a huge amount.
Yeah, the idea is to increase the damage a little. I always took issue with the fact that a lion can power attack all of his claw attacks without taking any extra feats, but a dedicated TWF can take three feats and still not be up to par with damage. Considering the damage dealers in the party consists of the two weapon fighter and a monk with only 12 strength, I'm not concerned with them doing too much damage.