Armor/Equipment merging.
Since Update 8, looting proper EQ with decent level became grindy and painful.
It would be cool to merge two identical items to raise it's rarity.
Higher the level/quality, more pieces would be needed to raise it. Or one item and proper rune cost.
And obviously, this wouldn't work on crafted items.
I just found this out after over 15hours of grinding Radiant Paladin set just to realise it's became common rarity after update.