He still needs a name though, any suggestions?
One of my character's name who wears blue is called Luino, sometimes ... Luin is "blue" in Tolkienish elvish ... You could make his name from Latin Caeruleus (variation would be Ceruleus) is blue (of sky (caelum, caeli), but I like the root of the word "goblin"/"kobolt" from cobalt (cobaltus, gobel(t), gobelinus (hence "goblin"))
Why not calling him simply Cobalt?
Anyway, here are some ideas ...