I recieved a normal version of Ashkandur, Fall of the Brotherhood and upgraded it to its max ilvl before equipping it.
This caused a bug where I lost the Normal variant of the sword’s transmog but kept the Heroic variant from upgrading it to the max ilvl.
I had learned the normal variant upon receiving the sword but I guess if you don’t equip the item before upgrading it the game forgets that it started out in it’s normal/previous appearance.