I would not use O1 tool steel, as it tends to get very brittle. Making O1 red hot and quenching it in oil will make it very hard, harder than a file, and will probably break on you. The art is in the color of the steel while heating, and picking the right oil to quench. You can search it pretty easy. When we make hand tools at work, I use flat 4130 in a normalized state, machine it and then heat treat it, in Caster Oil (old school, and a high flash point). I heat the 4130 just till it starts to barely starts to glow, then quench. When I make cutters out of O1 then its glowing red hot before quench. If alot of heat is put into the material in the cutting process (flame, plasma, hot tools), you might want to normalize it before heat treating.
I have also seen some beautiful tools made from 416 stainless, which can be treated.
Yeh heat treating is not something i can do or would want to do by hand with a torch for multiple wrenches.
Its pretty cheap to have them treated, electrically or in an oven
