Panpastel for weathering.
I was asking about some ideas for weathering hatch handles and items that may be worn down to almost bare steel. I gave these a try. They go on great and come in dozens of colors. I tried mettalic silver and metallic pewter. I applied after the dull coat so am not sure what might happen if you sprayed a clear finish over it.
My skils are limited but I did find this much easier to apply with the effect you are looking for over drybrushing liquid paint.
https://www.hobbylinc.com/htm/pna/pna29215.htm