I think that to start off with the system should be simple.  Disassembly by NPC blacksmiths for a fee.  You get a weapon kit back.  You work it back through the process to a handle and blade, then do what you what you normally do with those items.  This would also allow more freedom in crafting with the ability to work anything backward through the steps.  Bonus, an improvement to the "reality" of the game.

So imagine the above integrated and debugged.  Working fine, considered very stable.  /me grins

Next, implement the system for another job.  Lets say enchanting.  I do not know anything about it so I will not make myself look stupid.

Next imagine the enchanting and weapon subsystems are implemented, debugged, and at stable release.  Now we combine them.  An enchanted weapon cannot be disassembled without some risk.  After all, the enchantment was on a complete weapon so who knows what will happen when the mass that holds it together is broken.  Now we need an enchanter(ess) to remove the enchantment first.  In the process the magic user gains xp, or maybe can learn an enchantment that only exists on looted items.

An exciting idea, but it should begin simply I think.  Being able to reverse the crafting (or any profession's) process would be a wonderful addition I think.