I haven't write a critique in a while, so bare with me here~
1, I really love your brush style and the over all mood. You've always been very good at creating an rather expressive painterly feeling of your art. And I just love the background, I hope i can do that one of those days~
2, the composition is dynamic, with the horse and knight swingin his sward. However, the horse's rare legs got "cut off" at the frame bothers me a little. It'd be nice to see the full figure of the horse, would create a better, more complete composition.
3, I know you're trying to achieve a upside down triangle, to create a dynamic composition. and the figure successfully achieved that. But, the stone on the right hand side in the background broke your composition. Check out this little drawing I made to demonstrate my point.