Hello :) Cool Jedi !
Yeah the pose is a bit flat-rigid indeed.
If the light-sabers are ignited there is probably danger, so no straight back pose. You could use a martial artist picture as reference.
Or draw from imagination. Artwod gives blog helps on that :
- You have good shape
- You have ok proportion
- Try rotating the main axis of the body : neck, shoulders and the pelvic bone.
preferably not parallel to each other.
I'm not an expert myself, but it is what I try to do.
Hope It helps.
(in purple are your lines that are highly symmetrical, in yellow my proposition)