I don't know why I didn't think of this before (or maybe I did and just didn't write it), but Sephiro and the Demon Lord look almost entirely human (minus the horns), so why does Ike even need to hide his face at all?
He still gets acknowledged by people who see his face as a general in the Demon Lords army and even his subordinates who see his face don't seem to care.
It doesn't actually matter at all to me but I do find it funny.