Read from the World of Warcraft client build files (JournalEncounterItem, JournalEncounterCreature, Achievement) and the Blizzard Game Data quest API.
How Devoted Plate Walkers Compares
Who It Suits
Plate is the armor type Death Knight, Paladin and Warrior wear. With Strength or Intellect, Devoted Plate Walkers suits Arms, Fury and Protection Warrior; Holy, Protection and Retribution Paladin; Blood, Frost and Unholy Death Knight.
Transmog Sets
Devoted Plate Walkers is part of the transmog set Dorn Defender Armaments (Warrior, Paladin and Death Knight only). The other 16 pieces:
Blizzard numbers items as they are created, so the named items next to ID 221123 (221118 to 221128) were usually added in the same batch as Devoted Plate Walkers: the same quest line, zone, vendor or reward set.