I think background wise you should use a different colour. It goes well with the fire but it throws the value balance of the piece out of whack and makes focusing on the fire a bit harder. Fire always looks better on a darker background of course, but that's one suggestion. Pose wise he's quite stiff, the gesture and action of his arms don't match that of his torso or legs and it looks a bit awkward - like he's fighting with his arms but his body is relaxed you know? The rendering is coming along though, and the armour looks super cool!