Blessed Leggings of Undead Slaying

Blessed Leggings of Undead Slaying are an leather leg armor. It gives bonuses to agility, stamina, attack, and haste. It seems to have a unique model.

Source
This item drops during the Scourge Invasion event from the Scourge invaders located in Blasted Lands, Azshara, Burning Steppes, Tanaris, and Winterspring. The drop rate is significantly more common from the Shadow of Doom elites or rare mobs.