The duel prior to the ending was just head scratchingly absurd. Especially given the buildup; yes, lets ask a boon from a neighboring, hostile, empire to deliver over their prized prisoner so that we can have him publicly face Noble Idiot who has no skill with the sword... brilliant! I know he had to spare him to survive the encounter but at least try to make it sensible.
Also the war that dominated half the book being unwinnable, unprovoked and completely unnecessary from the start didn't help things very much either. If there were some purpose with an achievable goal and a cast of endangered characters that we were actually invested in besides the protagonist it would be one thing but as it stood each of his companions were more or less interchangeable and expendable, his love interest, forced and cliche. There wasn't even the excuse of an insane king with absolute and unshakable grip on power to move things along and make it tolerable, instead its revealed that this preordained disaster was necessary in order to fulfill a prerequisite of the main quest of the series
whatever.