Kerwin's self image issues continue as, even when Eston has been utterly defeated, he continues to look for ways to "outsmart" the terms of the unconditional surrender of his realm. Did he really think that appointing Cyrillos as Duke of Belegrond would be tolerated by someone like Elroy? You missed the back story, but Elroy let his only friend Zak die in order to make sure Arturius was emotional enough to break away and form Rieleston. He is heartless, and acting on his own personal vendettas right now.
Kerwin never even claimed to be intended to hold the Ducal seat for very long, given the disapproval expressed by several nobles– and that was prior to the treaty.
