If you have some pieces that you can sacrifice, try hardening in different quenchants (oil, water, brine) to see if it will harden enough to skate a file, and then do a break test: heat one end (in the forge or with a torch) until you have the full spectrum of temper colors running down the length, quench again, and then put each successive color over the edge of the anvil and tap sharply with a hammer (WEAR EYE PROTECTION!!!) to see where you get the right balance between hardness and toughness. Make a note of that temper color, and aim for that with your subsequent heat treatment.