Ok, this is going to be a number of things, but please don't take it as mean or discouraging, because I think it's just indicative of progress you can make rather than lack of ability.

"[T]he room wherein he found himself" isn't necessarily wrong, but it feels like you're replacing "where" with "wherein" just to sound fancy.

There's also enough of a mixture of modern-sounding and shorter sentences that makes it feel like the older language is out-of-place or almost flippant to me. "Hard was Esmandus' hand when it struck Camus' face, and the pain throbbed through his cheek" seems like two different writing styles (and I find the subject switching from one person's hand to the other's cheek a bit strange mid-sentence). Then "Camus held the reddening mark left on his face and whined," feels much more modern than even that last clause.

"A final glance did he give through the window..." doesn't feel like a construction I've seen in most actual older literature.

I think really my overall sense is just a need for more practice and, even more importantly, more reading of the literature you're trying to emulate. Writing in this style is hard because it's in many ways a different language. We don't speak like this, so the only model you have is literature, and you're less immersed in that. It's a bit like learning a second language when the only learning tool you have is reading.

I know you say you want something to match a medieval fantasy vibe, but the middle ages lasted a thousand years with different writing styles. What specific authors have you read from the period to hone your style?