In Aion there was an npc that could add an armor item as a skin onto another armor item (but not adding the stats).
Skin Purchaseable with gold/ep = Item A
Wearable dungeon item = item B (item B stats)
Go to npc to make item B look like item A and destroying item A in the process. (item B stats)
Another piece of armor = item C (item C stats)
Go to npc to make item C look like item A using item B (because B now looks like A) - (item C stats only)
You can restrict it so that only medium can armor can skin onto medium armor or open it up so that prophets can look like warriors or whatever.
For those concerned with HCS losing money because of people not spending EP, keep in mind that destroying item A means it would have to be re-purchased if skinned onto a bound item. You can also consider "unskinning" the item from the gear for re-tradeable purposes.
As the game grows, you can introduce skins for weapons, skins for shields etc. It would be nice if some of these skins were purchaseable in game, but other skins like a shield that looks like a car door, or a shield that looks like a big steak are only purchaseable through ep.