Read from the World of Warcraft client build files.
How Xuen's Helm Compares
Who It Suits
Leather is the armor type Demon Hunter, Druid, Monk and Rogue wear. With Agility or Intellect, Xuen's Helm 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
Xuen's Helm is part of the transmog set Xuen's Battlegear (Monk only), which the Appearances collection lists in 4 versions. The other 16 pieces:
Built from the World of Warcraft client build files and recorded Auction House snapshots.
Where Xuen's Helm Fits
Other Items Named Xuen's Helm
2 other items in the current build are also called Xuen's Helm. Same-name entries are usually a different rank, faction, quest stage or reward track of the same object.
Blizzard numbers items as they are created, so the named items next to ID 247107 (247102 to 247112) were usually added in the same batch as Xuen's Helm: the same quest line, zone, vendor or reward set.