Is Sigurd a demon or an angel? That’s a good question. I think he’s a demon, but a good one.
Sigurd is a legendary hero of Germanic heroic legend, who killed a dragon and was later murdered. In both the Norse and continental Germanic tradition, Sigurd is portrayed as dying as the result of a quarrel between his wife (Gudrun/Kriemhild) and another woman, Brunhild, whom he has tricked into marrying the Burgundian king Gunnar/Gunther.
Sigurd is Ragnar’s son. Ragnar is a Viking Demon and a descendant of the Norse god Odin. So that would mean, like his father, he too is probably a demon.