Which steels can be nitrogen quenched?
Any martensitic stainless ( all cutlery grades ) can be cooled / quenched in nitrogen gas. I presume it is gas and has significant circulation to speed cooling . The cutlery grades are all have very good hardenability and do not need rapid cooling. In my experience , nitrogen gas cooling would be very unusual ( not needed ) for martensitic stainless. It would be useful for quenching titanium ( type 5 , 6 Al , 4 V ). If you mean liquid nitrogen , no problem , probably . The very rapid cooling can cause cracking of complicated shapes. Various claims are made of the advantages of cryogenic cooling, some are true . But the possible advantages would not show up in a personal knife; they would show up in an industrial application cutting many tons of material per day.    HOWEVER , heating / austneitizing in a nitrogen atmosphere can be dangerous. Nitrogen can be absorbed into the metal and  stabilize the austenite phase producing a soft surface.