His legs could be longer and their current movement is unnatural. Starting position of his left leg is bad, like the knee is bent in opposite direction. You can fix this by moving those pixels up.
You change his arm thickness during the swing. The way he is holding a sword at the beginning of animation is very odd and distorted because arm is bended in elbow. His arm should be straight and hand with sword should be positioned away from the body.
As you said this is a great example, and you should break it in frames and analyze it carefully.
