You don't have to do anything. The dust is not only the fabric, but the epoxy, therefore should not be ingested, or breathed in. But, I don't ever recall a new micarta handle being dusty, a quick rinse with water or a blast of air from a compressor should solve any issue there.
Some micarta has been polished, some have not. You'll know just from looking, shiny or matte look gives it away, as well as the texture. Polised micarta won't soak up any water, unfinished micarta looks like fabric and will soak up water, dirt, oil, sweat, etc..but only the first layer will do so. The layers of fabric have been soaked in epoxy, and that will not soak up any water or oils, just the exposed fabric will. For example, if you stain micarta and then cut into it, you will find unstained fabric just under the surface.
The micarta can be washed off with dish soap and water.
Bark River does a wax polish on many of their micarta and G-10 handles, but also sell them as a matte, or non-polished micarta. When new, unfinished micarta has more grip, but get it dirty, bloody and it doesn't. After lots of use, the outer layer of fabric can become smoother, from grim imbedded into the fabric and/or just being worn off. Some makers sand blast their micarta to make it more textured and grippy. If you were to sand it, you'll make it cleaner, but smooth, just depends on the grit you use.
Hope this helps
