With skis, we use a P-tex candle to fill the big gouges, then smooth with a Surform rasp, and finally a wood scraper.
We also flatten the bases with a file, so a nice sharp file would also cut off any burrs sticking up.
Finally, we hot wax them, melting wax on there with an iron and then scraping it off with a plastic scraper. After that, they look smooth and shiny, and are as slick as you can make them on snow.
Since the bottom is not flat, you might try a heat gun, to melt the surface smooth, and then melt wax onto the surface to make it shiny again.