Consider if for a moment that your character didn't just gain loot from chests, or even from end rewards. Imagine if you defeat a named enemy and gain the ability to use some sort of magic/power based on it.
A spellcaster's eye allowing a character to use magic missile 3 times before it disintegrates. Possibly parts with timers so that after so many in game days, they disolve/rot/decay.
This would allow individuals even more freedom to customize their character, and be truely unique. Examples include but are not limited to;
A kobold shaman's eye allows the person to cast obscuring mist 3 times.
A minotaur's horn allows you to charge 3 times.
A bowl of giant's blood temporarily increases your strength.
Futhermore, when you obtain arcane texts from different missions like The Seal of Shan-Ta-Kor, or the Xorian Cipher you can use them to gain powers for a limited amount of time (provided you have a high enough charisma/wisdom/intelligence to read them)[each item would have a minimum charisma/wisdom/intelligence needed to read]
After all, it doesn't make sense for the texts to be so highly sought after and just take up space.
Ultimately, it would be wonderful if you could 'research' at various in game libraries and for casters to create temporary magic spells. Talk about variety.