Any rough file to remove the serration quickly, then finer to put on an edge.
I also don't think Dremel is a good idea. It does still heat up the metal, and you still need to file the thing down, creating a very high angle edge portion, not ideal for cutting, compare to filing down.
I also don't think Dremel is a good idea. It does still heat up the metal, and you still need to file the thing down, creating a very high angle edge portion, not ideal for cutting, compare to filing down.