That looks really good, Andy! What I'd do is try to work a little bit more shine into the lower parts of the helmet covering the cheeks and chin. They look a little too uniformly black and flat at the moment. Might be the pictures though, so you'd be the better judge of that. I'd also work a little bit of green into some of the dark areas. Not bright, fantasy-style verdigris, more in the tone of Vallejo Model Color Bronze Green. I just think it would give the metal an extra dimension. And, I would go further with the highlights. Use some brighter gold for the larger areas and for edge highlights you could go even further, mixing silver or some really light metallic colour with bright gold.
It really came out well, don't you think? Couldn't have been that bad, working with metallics? :curl-lip: