In Age of Conan... least I think it was in AoC... or maybe Vanguard... probably Vanguard... so many MMOs ago, bosses would not drop class specific item, but rather, slot "molds".
So for example, Turn 1 would drop say Head and Chest molds. Once you have a mold, you go to an NPC, and have the mold converted into the appropriate piece for your class.
If we want to make things more interesting... or time consuming... Have it require a specific item, like Rad-At-Hanz's Quenching Oil for 900 Phil, and maybe some 1 star item from the crafting class that repairs this equipment.
It is not exactly a token system, but it does solve the issue of 3 item sets being shared, and 3 being unique... and somehow dropping 2-3x as often as the shared ones.