I painted my wiper arms with some Duplicolor Bronze wheel paint. I was intending to do a long term weather test of the paint (it passed, with flying colors).

Easy job, sand, primer, paint. This stuff builds quickly, so two coats were plenty. It has just enough metallic sheen to keep from looking flat (even though it is non-reflective).
Maybe you could find some Gunmetal or Silver version of this "wheel paint".