Ullr's Robe takes the form of a kneeling, horned creature leaning on the signature sword. This Robe might be based on the mythical fire giant Surtr, a creature born from the flames of the region Muspellheim and a sworn enemy of the gods. His signature weapon is a sword of flames; during the Ragnarok he and his fellow giants will cross into Asgard and declare war against the gods. Ultimately, after killing the last god, Frey, Surtr will be the victor of the war, but will then use his power to obliterate himself and all creation until everything burns to dust.
The blue color of the Robe might represent blue flames, which are said to be the hottest part of a fire.