Your posture makes your shoulders look weak. Placing your left hand on your hip (or there abouts) and putting your weight on your rearward positioned left heel would have help that IMO. Those simple adjustments would also have shifted the left shoulder away from the camera and more into the shadow. A bit more mystique? Possibly.
Thanks for the advice, I'll make a point to remember that when I do shots like this. By weak though, what are you saying? I always love to photograph men to make them look soft, innocent and vulnerable, so if it's a matter of the posture not making him look masculine enough then I would prefer to keep the weaker positioning.