Read from the World of Warcraft client build files (JournalEncounterItem, JournalEncounterCreature, Achievement) and the Blizzard Game Data quest API.
How Ferroleather Chestguard Compares
Who It Suits
Leather is the armor type Demon Hunter, Druid, Monk and Rogue wear. With Agility or Intellect, Ferroleather Chestguard 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
Ferroleather Chestguard is part of the transmog set Ironpelt Garb (Rogue, Monk, Druid and Demon Hunter only). The other 16 pieces:
Blizzard numbers items as they are created, so the named items next to ID 139625 (139618 to 139630) were usually added in the same batch as Ferroleather Chestguard: the same quest line, zone, vendor or reward set.