Items, NPCs, quests, objects and spells of patch 1.12.1, read live from the realm itself.

Desecrated Pauldrons

NPC	Level	Zone	Chance
Grobbulus Boss	??	Naxxramas	33.3%
Patchwerk Boss	??	Naxxramas	33.3%
Gluth Boss	??	Naxxramas	8.33%

Quest	Level	Side
Dreadnaught Pauldrons	60	Both
Bonescythe Pauldrons	60	Both