The Death set was given to Hanzo by none other then Kayaba Akihiko, or more known by the name Heathcliff. They met once in a dungeon, And Hanzo was expecting a fight with the leader of the front lines, but to his surprise, He handed him a powerful set of equipment. Heathcliff told him to make good usage of it, this was rare, but he knew that Hanzo was the only that could use it well.
Sword Art Online
Grim Reaper's Robe
Night Vision: +50
Special Effect: Makes no sound while running
Special effect: Can be use as a Shield