I would like to see a new shopkeeper added to the game.
This shopkeeper would, got a crowns only cost, upgrade any piece of crown gear the purchaser chooses that they have in inventory or equipped.
The upgrade would be based in the purchaser's level and school, might have a chance to add or change the type of card(s) (if any) that piece of gear was attached to, and would change the look of it slightly - perhaps add a texture pattern or an extra piece (shoulder pads, a belt, bells on the toes of boots and so on).
Granted, this is not an easy addition, but then there are lots of new things going in all the time that aren't real easy.
But this would greatly enhance the player's enjoyment of the game and get a lot of people to spend more crowns, resulting in increased revenue for KI as long as the upgrades were worth the amount of crowns they cost.