First thing first. I think you may want to look at this:
shattered-earth.deviantart.com: Art Cycle It explains why we are stuck when doing art.
Now for this particular piece. I think you may want to work more on leg muscles that gives a stiff feeling especially on the knees (and the pose seems unbalanced like he's going to fall).
I took a look at your gallery. There's a lot of great things. You've got some diversity in drawing, some coloring skill (I think the warhorse is the most interesting in term of volume, shadows and highlights) and the pose usually seems quite natural.
I would say that you need to work more on the faces volumes (you often "hide" part of the face in 3/4 poses, like there's only one ear and one eye) and on materials (you shade a metal blade the same way you shade the body).