More complex bonuses granted by the equipment. (for example: Set gear grants new spells that can't be obtained otherwise. More parts of the set you wear, more powerful the spell becomes)
This seems to me a very nice idea !!
I like to see some more equipment-item that have the skill "Lockpick" on it ... so far( level 25) only Jagon's Necklage have it (and that's a quest item - I can only keep it by failing that quest and missing twice a quest remward !).
On 7th of february 2015 : I start a new adventure in the Divinity world of Original Sin, it's a Fantastic Freaking Fabulous Funny ... it's my All Time Favorite One !