The only problem I see in this is with the Guild Hats. But they can have a lock which is easy to script.
I think with the rarity rating it got no use. If players get spammed too bad.
If someone plays RunesCape (kind of quitted it) than you might know the trading system there. People send in the stuff they want to trade and than both have to press accept. After that a window will appear asking again if you are sure and it lists the items you will give and the items you will get.