Zandalar Demoniac's Mantle

The Zandalar Demoniac's Mantle is a cloth shoulderguard for warlocks. The mantle is part of the armor set called the Demoniac's Threads.

Source
The mantle is a reward for the quest Paragons of Power: The Demoniac's Mantle given by Al'tabim the All-Seeing on Yojamba Isle in Stranglethorn Vale.