This idea is full of fail. First of all, you don't have to understand how a weapon works to operate and even maitain it. Second of all, crafter-fighter builds are even more copy-pasty than powerbuilds, because to get the profession there's not much you can do with your SPECIAL and perks - so we'd have a clonewar in no time, most perks would become unusable and BG would rule the wastes because they save you a lot of points you'd otherwise have to invest in luck. Basically, you can't eliminate powerbuilds from the game, because they are a consequence of player mindset and not of mechanics. If you have a character creation system you obviously are going to have optimal ways of solving shit - so the powerbuilds will always be there.
Oh and avv and his usual bucket of bitching about how everyone is unoriginal and how you can't fight without a weapon skill. Yeah, you're right - now go and play Diablo 2, choose a Barbarian, invest all your character points in Magic and whine on Blizzard.net about how that build fails and how the game is imbalanced, lol.