Blood Guard's Plate Greaves

The Blood Guard's Plate Greaves are the plate footwear of the Horde PvP-Rare Warrior set called the Champion's Battlearmor.

Source
This item can be purchased from First Sergeant Hola'mahi located in the Hall of Legends in Orgrimmar. It costs 4125 Honor Points and 20 Arathi Basin Marks of Honor.