Whilst browsing my local surplus mdse store I came across some boxes of files. One box contained some about 10 or 12" long, 1.25 wide that were beveled from one side to the other with a sharper primary bevel to almost a knife edge. The thick edge was maybe 5/16" thick.
But there were no teeth on the flat sides, just a smooth surface. The only teeth were straight, across the thick edge for about half the length. That edge then had a rounded taper to a width of about 1/2" at the very end. These were made by Nicholson, and had a tang like a regular file.
I've never seen such before. Can someone explain the purpose/use for these?