I think animation is really fun, once you get into it. Seeing your pixels come alive is awesome! You just always have to choose to do it the hard way: frame by frame. This is a nice looking sprite, give the animations the time they deserve and it will really pop.
The problem I see in this animation is that it seems like you were just trying to get it done with. It's not bad, but it's not really good either. It looks like you just shifted the entire torso around each frame, and then re-drew the legs. There is so much potential aside from bouncing on his knees. Get up, put your sword over your shoulder, and get ready to attack something. What are you doing with your body? It's unlikely that both your arms are locked rigidly in place while you mechanically slide back and forth.
Movement has a shape of its own. It speeds up and slows down. See how your guy moves back and forth at a constant speed, with instant changes from one direction to the other? Things (including people) don't move like that. Movement has inertia, when it starts moving one way it requires a force to change. A lot of animation is demonstrating inertia and these forces that act on an object.
Here's a rough edit, just quickly exploring a few possibilities (the raised arm can bounce, the hanging one can swing, the shoulders can be lifted and dropped, the torso can squash, the highlights can shift, etc...)
Sorry it's not animated I can't export GIFs right now. Try it at 15/100ths per frame.
