Read from the World of Warcraft client build files (JournalEncounterItem, JournalEncounterCreature, Achievement) and the Blizzard Game Data quest API.
How Vilescale Helm Compares
Who It Suits
Mail is the armor type Evoker, Hunter and Shaman wear. With Agility or Intellect, Vilescale Helm suits Beast Mastery, Marksmanship and Survival Hunter; Elemental, Enhancement and Restoration Shaman; Devastation, Preservation and Augmentation Evoker.
Transmog Sets
Vilescale Helm is part of the transmog set Darkwatcher Bindings (Hunter, Shaman and Evoker only). The other 16 pieces:
Blizzard numbers items as they are created, so the named items next to ID 121319 (121311 to 121324) were usually added in the same batch as Vilescale Helm: the same quest line, zone, vendor or reward set.