I got one of those once and had a devil of a time with it. I just used sandpaper to clean it up. If I had it to do over again, I would treat it like frizzens. I would anneal it FIRST. Then I would file and polish, and re-heat treat when I was done. I have ruined too many files, hones, etc... on metal the was not fully annealed. Now, if it is too hard to work, it gets annealed. Sure, it takes a while, but you can do something else while it is cooling.