Item is no longer available to players. It was an item drop from Zul'Aman. ZA was removed as a raid in Cataclysm and re-introduced in 4.2 as a heroic-only level 85 dungeon.
Patch 5.2 re-introduced gear models/colors from the original Zul'Gurub and Zul'Aman. See Faded Spirit-Wrencher Robe if you want the look of Robe of Departed Spirits.