(how do you explain that - he can hit faster? Perhaps he can weave his way through his opponent's guard - in that case, make that his hits either cannot be parried, that you can force a parry reroll from the enemy or that he can cancel a single parry of his).
Basically he's learned to use both hands at once. It's hard to do but you can eventually start using them
Powerful build should go, yes. So should Fey Quickness. I just think we should replace the both of them with new, original and useful skills.
I like fey quickness, it's a full skill slot into a 6+ ward save. It's not bad.
My point is, we need to stick with one single effect (and the "extra attack" is a bit of a waste, when we have the possibility to go ahead and make something original).
You may have noticed that several of the core skills include multiple benifits (such as combat master, with +1 attack and immune ot all alone).
The possable waste of a skill was why I wanted to have it scalable so that every attack on profile gained you an extra attack for the offhand weapon.