It's really bugging me, that whilst the shading you've used might resemble metal, it doesn't define actual form that well. I think using more basic shading and refining and adding lots of white for the highlights would yield a better result. There is a lot of banding and excessive colours. Once again, I think shading with far less colours just to define the form and later adding more colours and detail if necessary would improve this. As noted, before, the forearms are too small, as are the shoulders and torso.