I agree too, but imho, if I were Acheron, I think I would also like to improve my collection further more.
So... how about Acheron the mad collector, who would go after any unit/city with magical equipments, starting from Orthus' Axe to Crown of Akharien (not sure if I spelled them right), and would foolishly leave his treasure under a guard of a few orcs = easy target for both a player and AIs.
Of course, he would at some point come back, found his treasure stolen, and try to reclaim it in rage.
Moreover, when he founds his treasure dismissed in wilderness and his city already razed by the thief, he could also go and capture a nearby city as his new bed. (so could be abused to make him attack rival civs)
Also, maybe having all or most of the equipments droppable on a city would be nice too, so that he could add them into his glorious collections