Thats it bud, basically....
Take an Old file, put it in a fire as long as it glows bright red, and cools down slowly then it will go soft.. its called annealing, as your not controlling the process the softness may differ, if it needs to be softer do it agian..
Take it out when cold, mark it up to what you want.... cut/grind/file to shape, including the bevels/grind.. drill any holes for the scale pins
.
To re harden, heat to red hot and quench in oil (Keep it moving untill the flames stop then put in water. .. it will go hard at this point check with another file, if it skates over the surface its hardened, if not repeat this stage, when hard you will not be able to do any more file work to it but it will grind but be careful if you do or you will soften it, if it gets too hot.. ie turns blue..
Then to temper - or it will be too brittle
Clean surface of all the black back to shiny.. Carefully heat until you see a straw colour appear at this point Quench in oil again.. if you go to blue the blade will be too soft
.
Thats it in a nut shell.
BTW used engine oil is good for the quench
.. oh careful thing will be HOT, lol..
.. or heavy.. it depends on which excuse you use as you drop it...lol
Clean