Remember that mission on earth where you went after the house of kings? It was in the rocket yard near where the servitor spawns sometimes. Before how you could glitch in there and when you got to the end there was an ultra archon. May not have been an archon, may have been captain or something. However it was ultra _____ and just a big yellow bar guy. I think he was there as a placeholder or something because the area wasn't finished yet. I think you might have found another of his name is 'ultra knight'