Read from the World of Warcraft client build files (JournalEncounterItem, JournalEncounterCreature, Achievement) and the Blizzard Game Data quest API.
How Sinstone Shoulderpadding Compares
Who It Suits
Cloth is the armor type Mage, Priest and Warlock wear. With Intellect, Sinstone Shoulderpadding suits Discipline, Holy and Shadow Priest; Arcane, Fire and Frost Mage; Affliction, Demonology and Destruction Warlock.
Transmog Sets
Sinstone Shoulderpadding is part of the transmog set Depraved Beguiler's Visage (Priest, Mage and Warlock only). The other 16 pieces:
Blizzard numbers items as they are created, so the named items next to ID 184137 (184132 to 184142) were usually added in the same batch as Sinstone Shoulderpadding: the same quest line, zone, vendor or reward set.