Patch 10.1.7 added an achievement that requires players to defeat Nefarian while having Onyxia Scale Cloak equipped.
Patch 10.1.7 adds an interesting achievement called That’s Just Cruel. To complete it, players must defeat Nefarian within Blackwing Lair and Blackwing Descent while having Onyxia Scale Cloak equipped.
That’s Just Cruel: Defeat Nefarian within Blackwing Lair while the Onyxia Scale Cloak is equipped. Do the same within Blackwing Descent, just to get the point across.
The achievement is not exclusive for Leatherworkers even though the game lists it as one. To complete it, you can buy Onyxia Scale Cloak in the Auction House and defeat Nefarian in both raids.
This achievement they added in 10.1.7 is pretty funny
byu/Grayvves inwow