This when I first looked at it, I couldn't really see anything truly off about it, so I copied it into SAI and flipped it.
First thing I noticed is she's slightly off balance. She's got a little bit of a lean to her that can be fixed pretty easily. The next few things are little things that can help you push her pose.
Her hand holding the spear(?) would benefit greatly with some more exaggerated foreshortening. Make it bigger, not by much, but a little bit, and it will give her a little more depth. Her shoulders could also benefit from being broadened just slightly. If she's hefting around a spear and a massive shield she's going to bulk up there a bit.
Also her shield is a bit skewed looking, though I'm not sure right off how to fix it.
The biggest issue I saw was her feet they are sitting on the same ground plane and because of this the leg pointing towards us is shorter than the leg pointing away. This isn't something everyone realizes when drawing, and it can cause a lot of "why does this look weird" moments. I strongly suggest lengthening the leg that is coming forward just a little bit.
When drawing remember to consider the perspective of the area, the ground isn't just a level straight line, it extends behind and in front of the character and you should use that space to push your posing.
I did a quick redline to show what I mean in all the above. Unfortunately I wrote on it while flipped so I'll keep it flipped for this.