Who It Suits
Leather is the armor type Demon Hunter, Druid, Monk and Rogue wear. With Agility or Intellect, Arinor Keeper's Vest suits Assassination, Outlaw and Subtlety Rogue; Brewmaster, Mistweaver and Windwalker Monk; Balance, Feral, Guardian and Restoration Druid; Havoc, Vengeance and Devourer Demon Hunter.
Transmog Sets
Arinor Keeper's Vest is part of the transmog set Arinor Keeper's Leather Armor (Rogue, Monk, Druid and Demon Hunter only). The other 16 pieces:
Built from the World of Warcraft client build files and recorded Auction House snapshots.