I think it needs brighter highlights:
Heres a good example I fount of a golden helmet that I think might help.
On your guys helmet I would put the light higher on the helmet and have a lot more drastic change of light and dark in the gradient. Gold is generally a brownish colour but because of the light reflecting on it it appears yellow or orangish. You can tell how usually the gold goes from light to dark in a fairly short amount of space. Because of this I would add alot more and darker shadows on it with hotter highlights. Also notice that it is fairly... Muddy I guess. Real gold isn't usually very reflective so it blurs the highlights out.
Hopefully this helps I feel like I might have done a poor job of explaining.
