Hi,
L&R frizzens are SAE 1095 steel. At one time they made them from steel with 1% carbon by weight. Heat it to bright reddish orange with a MAPP gas torch and quench in warm canola oil or quenching oil. Motor oil stinks badly and canola will cool the steel faster. Clean it up and then heat it to 375 degrees for 1 hour in an oven. Finally, polish up the toe of the frizzen until it is bright and shiny and use a mini torch or propane torch to slowly heat the toe until it turns blue. Have a little spray bottle of water handy to cool the rest of the frizzen if the color starts to migrate up to the pan cover and frizzen face. However, before doing any of this, make sure the frizzen fits well on the pan because it is much easier to file it to fit before any heat treatment.
dave