Holzwurm,
After case-hardening the frizzen, heat soak it for 1 hour at 400 degrees F. Let cool slowly and polish it back to shiny steel. Then heat the spur, toe, and pivot screw hole area with a propane torch until it turns dark blue. I keep a spray bottle of water handy to cool the hammer part of the frizzen if the blue color starts to spread from the spur. Jerry Huddleston described this method in a post several years ago.
dave