This is going to be a relatively short suggestion so please feel free to extend it in the replies. The main idea is that for armour you would have vanity slots and actual armour slots. Basically you could be wearing mithril armor for protection and Gondorian Armour for vanity. You would appear as if you were wearing Gondorian Armour but you were actually wearing mithril. This feature would not be good for multiplayer combat because you might think someone has iron armour but they have mithril armor on. The durability would drain the armour you have in your "protection" slot. I suggested this because I like the look of the Black Numenorean armour but it does not provide much protection. In conclusion, a stupendous idea for singleplayer, but very unbalanced in multiplayer. If you have any ideas of how to make this good for multiplayer please post them in the comment section of this suggestion.