Re: [DF] Puissance
 

There are other sources of "per dice" damage bonuses in Dungeon Fantasy: Double Swords and Tempered Glass weapons, both on DF8. If they don't stack, and they don't stack with Weapon Master, then I've been playing it wrong, but the text is less than clear. The way I read that thread is that skill-based per dice bonuses do not stack. You can only get the damage bonus from having the skill at X once, even if you have two sources providing the bonus (Karate and Weapon Master for the bladed hand, Throwing Art and Weapon master for thrown weapons)

Re: [DF] Puissance
 

I would never hesitate to stack bonuses coming from distinctly different sources. I also think that Magic in GURPS is too limiting for many genres, and would not see any problem with bumping Puissance up to +1/die, or otherwise just making it more effective. If you look at the damage potential of many fictional enchanted swords, they can be very hard to recreate by RAW...