Hello there, and welcome to Pixelation!
This looks like a very promising start, I hope you keep with it; It can be a really cool piece.

If you have problems with small faces, you're in luck, because with the lighting situation you set up, you don't really have to put much detail into the face at all. The one you have right now actually is good for what it is, but you're overestimating how much light would be reaching his face. It should be closer to a rim lighting scenario, where it just hits the edges.
When you sketch, I would suggest using a 1 pixel brush, might help from things getting to messy too fast.
Speaking of messy, your image has 109 colors. Make sure to use tools that allow you precise control over your palette. a mostly monochromatic image like this needs no more than 16. I reduced my edit to 16 and there is barely any loss of information at all. Anything else could be solved by better spacing of value between colors.
I felt the posing was a bit awkward, especially the hand with the sword. You might want to play around with different poses. The feet are also a bit awkward and boring. I can understand wanting to make the sword a focal point, but it can be done in better ways I think.
While the handling of the palette is messy, the general idea with the colors is good. Creates a definite mood. almost a cinematic touch. Strong sense of lighting, and the composition is simple but effective.
Good luck on this piece, and I hope this was of some help
