Pika what is the mehod to heat treat a saw blade? I have treated mild steel shafts bye heating to a straw color and burying in a can of powdered lime. This greatly slows the cooling process. Havent broke one yet but havent stressed one to terrible either. As for treating a file to make less brittle would simple annealing help?
To all those reading, I sugested a file for knife making because most people have a old small file around. This makes it a inexpensive way to start. Hard and Brittle, yes as Pika says . Good practice in begining knife making? I think so, with care they can be servicable, Best maybe not ,but servicable.