Hi,
One other option you might try on your G10 grips to darken them again without slicking them up is what I and a number of other custom knifemakers use on the G10 handles for our knives, and that's mineral oil.
I'll apply it with an acid brush or a cotton tipped applicator, wipe it off with a clean cotton cloth and blow the textured part out with compressed air and it's good to go.
Les Halpern with Halpern Titanium, who fabricates a huge number of G10 scales every year, shared this idea with me years ago.
Hope it helps.
Jim