The lower austenitizing temperatures provide the best impact toughness by leaving mushy structures and lath martensite. Great in a coining or cold forging tool, though not always ideal in a knife edge.
There are several kinds of "edge retention". There is edge retention related to abrasive wear resistance, which is largely a matter of the chemistry.
There is fine edge stability, which is largely a matter of the structures formed and the structures avoided and has less to do with chemistry.
There is also gross edge durability in rough use which is also largely a matter of the structures formed and the structures avoided, and related to, but not the same, as edge stability. Austenitizing temperatures and tempering temperatures play an important roll, as does the use and timing of cryo, various soak times, quench rate and material condition going into heat treat.
I use 3V quote a lot, and I use an optimized HT for it that is a little different for small knives verses large knives subjected to impact. This is because edge retention needs are different for different knives because they go dull through different mechanisms, depending on use. My 3V choppers end up at HRC 60.5 and my smaller knives end up at 62, but not because these hardnesses are the ideal hardness, but because that's where they ended up when the best structures were worked out for those applications. Or, to put it another way, the larger softer knives are not the same heat treat as the smaller harder knives but just tempered back. Quite the opposite, the smaller harder knives actually have a slightly higher tempering temperature. The harder knives are harder because there was more carbon put into solution in order to force plate martensite. This plate martensite gives a crisp stable edge that is more durable in many applications (lateral load on the edge), but less durable in others (impact on the edge). There is more than one way to put carbon into solution, not just aus temps, some involve multiple steps.
My point here being, edges deteriorate though various mechanisms, and the ideal heat treat for a particular knife needs to take into account how it will mostly likely go dull and be optimized for that use. The hardness is not the important thing to focus on, it just lands where it lands, the structures formed (and avoided) are what is important. At least in 3V. There is very little information on 3V in the literature, but you can look at other steels with some similarities such as M2, and see very easily the potential drawbacks to the higher aus temps, so be aware when you start playing up there your grain is still going to be fine (grain growth concerns are largely moot on 3V on your first heat), but your RA can be really bad, and addressing RA in the quench gives different results than addressing it in your tempers, meaning it's not just important that you address it, but also how (when) you address it, and sometimes it's best to just avoid it, particularly if you're not using full cryo.
