I'm pretty sure it doesn't even if it's been a while.
This is for enhancement right? Getting a weapon to +9 doubles the damage range you can inflict as stated on the weapon description. It however doesn't literally double the damage you do with actual spells/skills so defense is taken into account first.
If it's for stats from greens/blues, that also does not bypass defense.
It's a good thing it doesn't, then, because it keeps all the weapon types relatively balanced. If it did, and I had been suspecting that it might, then a hell of a lot of axe fighters would be feeling pretty stupid right about now.