Anza knife company makes knives from files. The files are too hard and brittle for a good knife blade so they need to be annealed some by heating to a moderate temperature for a time and then slowly cooling. The steel becomes less hard, but is also less brittle. Then comes the grinding, polishing and mounting of handle.
Making knives out of files is what we did in Jr High, our grades came from the chisel we had to make from bar stock.
Same thing he did/they did in class but then reheated and placed in cow hide shavings to cool.