I hate animating stuff. I might try to make her arms swing out a little more than they do now. I don't want her too dynamic because she's supposed to be walking and not running, so she'd look like she was having a fit or something.
Agreed, don't have her swinging her arms too much. In fact, presently, perhaps there is too much movement (swing) from elbow to wrist/hand. That is, her forearm is "hanging" + swinging from her elbow—
I think this is the main thing: instead of her arms "hanging" from her shoulders (or her forearm "swinging" from her elbow), have a subtle, but deliberate, shoulder-shifting-forward + upper arm follows suit + forearm (I don't know what will look good, maybe the forearm could be 1-2 pixels more dynamic than shoulder+upper arm shift).
Anyway, I love your work and I know that the subtleties (of animating sprites) can be quite frustrating.