I'm just doing my thing here, but maybe there's something for you to use in there:
Metallic: I like to do nonlinear gradients such as (1). Sometimes I pop the highlight, sometimes I don't. Sometimes I don't even go up into the brights. Too many highlights are distracting, so place them at points of focus.
Linear gradients like (2) can be useful but are mostly not useful for describing form and contrast.They're just sort of easy to make (IT'S A TRAP!).
What else. Yes, I often add a dirt and sky color to my silvers. Planes facing down tend to reflect warm colors, and planes facing up tend to reflect cool sky colors. If we're outside playing in dirt that is (knights often were, I suspect).
On a small character like this you generally don't need a whole lot of colors. There's simply no room for elaborate gradients. Each pixel is more likely to play a role in showing some kind of detail or contrast point.
