Instead of outlining in black maybe try a light brown or dark brown? Also, give it more curve, it needs to go on a shoulder so make it seem like its already on a human shoulder but it really isn't and make it curved that way. Clean up the black and white shading on the middle and bottom part of the shoulder metallic area, add some scratch's and sword marks making it seem like this has been through war. The bottom half of the shoulder throws me off a little bit, I keep thinking this is a gauntlet or metal gloves, so for the bottom half I would make it not so long and maybe add some designs/symbols on it.