inlaying wire and then sanding or filing it down to flush leaves scratch marks in the wire, no matter how fine a paper you use,...although very fine, when you wipe over them with finish, you fill the scratches with stain and finish, which dulls the reflective property of the wire's flat surface.
lightly scraping over the area of the wire inlay with a very sharp scraper will remove a lot of those scratches , so the wire holds less stain color and finish.