WhatIsUnique adds a line to item tooltips when it finds an item which has a unique model. This currently only supports weapons.
All Stable Releases of WhatIsUnique are automagically packaged on Curse and available through the Curse Client. The addon can be downloaded from the WhatIsUnique Project Page using the manual function or the client buttons.
If you are interested in contributing to the addon or just want to check out the code feel free to check out the WhatIsUnique Source Code on Github.
I ask that all problems with the addon are reported to the WhatIsUnique Issue Tracker on Github. Checking the Curse project page can be a bit of a pain in the ass sometimes and it helps me if I can keep everything organized in one place.
Thanks for checking it out and I hope someone else can make use of this addon!