Considering stats on gear can roll 20% higher or lower then the average, what about a system to re-roll or straight up increase the stats on gear?
You could pay/sacrifice Legendaries to slowly increase the stats on a piece of gear towards the highest possible rolls.
As the rest of the game is all about RNG, it feels wrong to have a guaranteed “do xyz” to have the ultimate rolls on any item you wish.
Yeah fine as a mod, but not something I personally would like to see in the base game… still just my view 
If it re-rolled the stats with no guarantee it would turn out better, so long as the cost is on the high side (to prevent spamming of this ability), i’d be OK with that.