What is Argon's role in the novel, A Vow of Glory?

Argon appears to be some sort of god or apparition who serves as an adviser for the ruling member of the MacGill family. Argon appears twice in this novel, once as Gwen watches Kendrick ride away to rescue the two sick girls and the second time before Gwen surrenders to Andronicus. He is the one who has told her that she must die a little death in exchange for having asked him to save Thor’s life. Before he leaves Gwen, Argon tells her that she has done the gods proud.