I think maybe just the overall concept and side view of pose is just too flat and stiff, there is a lack of energy. I don't get the sense that she just cut someone with force. With some foreshortening and perhaps a change of camera angle with a feeling of movement I think this can go farther. Maybe consider her using two hands for the sword. Is that a katana? I believe those are two handed. Even a long blade needs two hands. Perhaps thumbnails should be considered. It's fun to see the progress.