Definitely work on the follow up. I didn't want to mess with your stuff too too much, but his body when he slashes is really still. A bit of hyperextension might work, but that could probably be fixed with a bit of hair movement. Everything about it is too still; the strands could swish across his face or have some sort of movement, something to carry the momentum. The top knot does completely still when he slashes. It might be because I duplicated a few frames for minor edits, but it can show some sort of movement.
As for the palette, I just made the colors a bit more saturated. The darker skin tone you had was a bit too close to the main one, but having brighter shades is better for visibility and making everything stand out against the rest, especially at this size. I also bumped up the red a tiny bit. You don't necessarily have to use the colors I put in, but I would personally put the ones you have now to be a little brighter.