The problem I see is that I, as a programmer, will come to your game terribly overpowered. I could instantly program in boss weapons and azng armor, etc. It'll be interesting to see how you handle this problem.
I've thought of this as well (for a general user-driven-content game-scenario) - Maybe there should be a quality assurance step? Either by picking n active users at random, add them to a testing stage with the item and let them rate it. They could be given gp and/or xp based on the time they've spent testing.
-Or a moderator could do the testing. Regardless, I think they should be tested by someone before being put inside the game world.
(Think of all the phalluses without QC!)