I've used the same kind of nail files to convex edges, and thought I was the only one. I was using them to give some scratched-up blades a new sorta-polished finish, then thought, if it works on the flats, it'll work on the edges, too! I even gave my Native III a full convex using the same kind of file almost exclusively (yes, it took forever, and yes, I have too much free time). It works for quick field sharpening, too, but I prefer a much finer grit for that when available. Oh, one difference, I run the file perpendicular to the edge, and though you run the risk of cutting into the file material, it just seems to work better for me.