[Crono]

Like my old suggestion, make event weapons tradeable for EXP and money. Possibly even ammo for other guns. This would make people trade their event weapons in, causing less event weapons to be around. If it still doesn't work, possibly have a lottery or something. You pitch in your event weapons and one lucky winner who pitched in event weapons (the more you pitch in the more chances you have of winning), gets some sort of uber weapon.