Mages will often pick up lots of charms and nicknacks over their lives. Some will just be symbolic, minor pluses for casting certain spells and some will just be pretty (not quite symbolic enough). Some will be things they picked up when they vanquished an “opponent”. Some of it might be useful to an Evil mage, while others might be useful to a Good Mage. Some might even be useful for you, but probably not. Since you don’t want to release this hard earned swag (others might use it against you, or somebody might realize you eliminated the opponent since you have their stuff, or it supports mages of the other side), you just hang on to it. Given enough time and research, you might be able to determine how to use all the items and destroy those that are dangerous to you. For now, they are just in a nice jewelry box you have stashed away.
Of course then you die and all your heirs see is a box of cheap nicknacks and minor antiques. Such is the problem with being a secret Evil Cultist or magical super hero.