Some excellent notes there about steel used for knife use from Tom_L. Stainless Steels are used in preference to low alloy carbon steels mainly due to their abilities to resist corrosion. Corrosion resistance is also important to many and the higher carbon value stainless steels corrode more than the lower carbon valued stainless steels. S30V, 154CM and VG10 are all excellent for knife making. The 'lower' specification knives made from AUS6, AUS8 and 440C just need sharping a bit more often even though they are tougher but not as tough as a TI6AL-4V titanium alloy knife (holds an edge even less than the stainless steels but all the stainless steels mentioned are nowhere as corrosion resistant). Loose one material property gain another!! This is why there is Damascus Cowry composite steel.
This is why I like the knives produced by Helle and Fallkniven where they use a laminate construction. Generally a plate of VG10 sandwiched between outside steels of 18/8 stainless in the case of Helle knifes, which is tougher and more corrosion resistant. The VG10 having a rockwell hardness of greater than 59. I think they represent excellent value in a modern knife. Fallknivens Super Gold Powder Steel technology looks interesting also.
I think your right about the minimum spec being the 440C also.
As for low alloy steel, I remember the days trying to cut and file down Reynolds 753 cycle tubing. A simple low alloy steel but with finely controlled heat treatment. Talk about being tough and hard, that is the steel I mean.