I don't normally associate with thieves, but I don't think they'd get very far with one arm. I can sort of see the shoulder, but where's the rest of it? What you'd be best off doing is having the right arm mimic the position of the left, which means that the elbow would be place approximately behind the cheek, and the forearm would be off in the distance, with the fist drawn down and to the left of the chin. While we're on the subject of arms, you could make the left one a little bigger, because given that it's proportionate to the left leg, it looks like they're on the same vertical plane. It would be more exciting if the left fist was larger and directly faced the viewer.

What else...the style of clothing is fine, but several things could be drawn a little more carefully. I'm thinking mainly of the crotch of the pants, the bag tied to the belt, the zipper, and that insignia on his breastplate. I get that this is supposed a be a sort of loose, cartoony style, but you've still gotta meet a certain level of quality to jump to "style" from "I can't draw this." With any sort of insignia or symbol on a character's clothes, you want to make sure that it's well-drawn and clear to the viewer-those things are part of what makes the character who he is. From this distance, it would be fine to draw just a straight line down the center of the shirt for a zipper. But if you want to make it more realistic, just make sure the zipper line doesn't touch the edges.

One thing that I think would really help your drawing is, when you're drawing a line that represents a clothing wrinkle, and then drawing shadows or highlights around them, keep those on one side of the line. It looks a lot neater, and it looks more like realistic light and shadow. I'm thinking of the crotch, the jacket, and the gloves. Speaking of the jacket, I'm willing to accept a little stylization, a little exaggeration, in this sort of drawing, but that stomach is just too thin. Make it end farther to the left. The curvature of the abs is good, though.

The dagger is good, but what are those other weapons supposed to be? They look like teaspoons. The right leg should be lower, to sync up more with the left one. On the right side of the left knee, (and keep in mind, when I say right and left, I'm using them as they would be on the character's body) draw the straps for the kneepad on the side. The other leg doesn't need them on both sides due to the angle it's at. The lower left leg would also be more behind the left thigh-foreshorten it more. The boot is alright-it still has that shading problem, but for whatever reason, it's not as big of a problem. I'd recommend getting rid of that silver thing-I think it's a shinguard?-on the left boot. Or else make it look more like a shinguard, because now it's digging into the foot.

The face is fine-really good, in fact, for this style. The goatee is a really nice touch, because it gives the character a sense of maturity and adulthood. The only complaint I have is that the right goggle lens would face more forward than off to the side. The background does it's job, but I've always thought that a straight gradient background is kind of cheating. Maybe use the Blur and Smudge tools to give it a more "whoosh" feel.

Conclusion: This is a nice drawing that has nothing drastically wrong with it (except the missing arm), but it could stand some cleaning up to look more like a finalized product.