Well i would not call it mistake. Interpretation of an artist (Licencja Poetica we call it in my country). But nevertheless i would have dificaulties guessing who it is without title. I think i would say it is, gargoyle or some kind of undead, maby male Banshee (althou i think there is no such thing) or some kind of Vampire.
Nice it is giving impression of power between them. I just imagined Icarium as more slim person, rather thin and tall than musculed (musculed one was Mapo). As i understand it his power were more spiritual in origin than phisical (althou it's effets were mostly phisical).
I think you have truely captured the struggle between two of Erikson's most epic characters magnificently. I am too inexperienced to comment in a way that does full justice to your artistic skills. Suffice to say the artwork is amazing.