I have a high carbon knife from the Philippines (a Balisong) and the steel has some streak staining (for a lack of a better term). What is the best way to polish those out? I have no idea how to do it. I considered a very fine sandpaper. My second question. There are some tiny dents on the edge of the blade and I tried sharpening it and most came out but there are tiny residual dents. Any recommendations? Lastly, is there a limit on how many times a knife may be sharpened?