Part of the Vindicator's Battlegear set:

The set gives these bonuses as more pieces are worn: 2: Increases your chance to block attacks with a shield by 2%. 3: Decreases the cooldown of Intimidating Shout by 15 sec. 5: Decrease the rage cost of Whirlwind by 3. Set Details | All Sets

Quest Reward from:

Level	Name	Start	Rewards
60	Paragons of Power: The Vindicator's Breastplate  (Raid) Horde and Alliance Zul'Gurub	Jin'rokh the Breaker Stranglethorn Vale	6600 XP