Post by SteeJans33
The message you're seeing is in regards to whether you are able to transmogrify a piece of armor/weapon.
At the end of the Cataclysm expansion, Blizzard added a transmogrification system. Essentially, you can modify any piece of gear to look like another piece of gear of the same category. For example, I can make my plate shoulders look like any other plate shoulders in the game for which I have unlocked its appearance. To unlock an appearance, you simply need to obtain the item, and equip it if it's a BoE. Once you've unlocked an item's appearance, you have it forever.
The message you are seeing, is telling you that it is an item which you have not unlocked the appearance for, and cannot be used in transmogrification.
To apply the appearances you have unlocked, you need to find an ethereal transmogrifier. You can find these guys in the Cathedral District
for Alliance or in The Drag
for Horde. They will let you change the appearance of any equipped item in exchange for gold.