It looks rather odd to me that the shadows on the character are lighter than the environment, which is more likely to be lit by ambient light.
How about switching the dark brown with the black? As a bonus, that'll give you increased contrast on the character and reduced contrast in the background, making the character pop more.
Here's an edit doing that:
I also:
- replaced the dark brown on the mountains and darkest red on the moon with grey from the castle to help the colours transition better, and reducing your colour count as a bonus
- made the hand on the sword's handle a little larger, it was rather small. That whole arm feels rather short though, so you may want to work on that. If it's meant to be foreshortened, you'll need to clarify that.
- added some extra transitions/detail using the dark brown from the new "background". Switching the colours around leaves you more room for that :]