This is probably too late, but I think the pose is too subdued for a Berserker.
But anyways, I think the metal looks fine. I never really bothered with highlighting metal, since lights did a good job of highlighting metallic paint.
If you mean the red parts, then I would simply suggest simply drybrushing a lighter shade of the color over the other armor bits. Only drybrush so that the lighter color is on the raised parts of the miniature.
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