Ups...I always thought they´d be wood, my bad.
But even if they´re the same as the grips on a Denix, you can archieve great result by lightly sanding them to get rid of the shiny surface and make them more wood-like. Then just apply a black wash and you´re done.
Anyway...I honestly dig the weathering you did!
Makes it look soooo much better :thumbsup
Markus