Read from the World of Warcraft client build files (JournalEncounterItem, JournalEncounterCreature, Achievement) and the Blizzard Game Data quest API.
How Thunder-Clad Legguards Compares
Who It Suits
Plate is the armor type Death Knight, Paladin and Warrior wear. With Strength or Intellect, Thunder-Clad Legguards suits Arms, Fury and Protection Warrior; Holy, Protection and Retribution Paladin; Blood, Frost and Unholy Death Knight.
Transmog Sets
Thunder-Clad Legguards 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 221034 (221022 to 221039) were usually added in the same batch as Thunder-Clad Legguards: the same quest line, zone, vendor or reward set.
Cowboy Bee[DNT]ID 221022 · Miscellaneous"Teaches you how to summon this companion."