If you heated to nonmagnetic and held it there for 10 minutes, I would expect it to get hard. Maybe not the full 67 or 68 hard, but hard. 52100 is heat treated in different ways by different people. Ed Fowler likes to go to just above critical and edge quench, and then do this three times. He may not be getting the amount of carbon in solution that he wants on the first quench, because he goes just above critical, no soak, then quench. Do this three times, then he has the carbon he wants in solution. Kinda what you did...only you just did it once. Yeah, it got hard, but probably not max hard. To do it all in one quench requires a 10 minute hold at 1475F, assuming the steel was set up properly to harden.
For example, Aldo's 52100 used to come heavily spheroidized. Not sure if that is still the case. But in order to get that heavily spheroidized steel to harden properly to 67, a full normalizing was needed first. If you didn't do the normalizing, you would get max about 63HRC. I would assume that is where you are at......IF THAT. Non magnetic is only 1414F. If you quenched AT non magnetic, you don't have near enough carbon in solution for max hardness. Just enough to maybe skate a file.
The Cr content in 52100 in no way makes it act like stainless. It is still very much a carbon steel, and is prone to corrosion. Not as bad as O1 maybe, but still there. Blueing helps to some degree. Parkerize would probably be a neat option, but I don't like blade coatings myself.
Back to the 52100 heat treat. Done properly, 52100 excels! This is a heat treat recipe developed by Mr Kevin Cashen, the GURU on all things heat treat related, for Aldo's heavily spheroidized 52100.....
1650F, then air cool. This gets carbides in solution, homogenizes structure, but at expense of grain growth
1550F, then air cool. This further refines grain structure
1450F, then air cool or quench. This further refines grain structure
you can do some subcritical steps here if you like, as in 1375F, air cool or quench.
you can go right to hardening from here. 1475F for 10 or 15 minutes, quench in 130F oil, canola works well. temper
if you need to do more machining, after the 1450F quench, hold at 1200F for a few hours, then air cool. Or do a few subcritical cycles, either way, then quench
Point being, if the steel is supplied in coarse (heavy) spheroidized condition (I think it still is), to get most out of blade, you'll need to normalize at least.