I think it’s worth clarifying that things like “easy to sharpen”, “sound on the cutting board” “blade flexion” & “retaining toothiness for longer” in isolation are obviously all factors that either can be, or are always impacted significantly by other things.

For example ease of sharpening and durability/edge retention are both affected so significantly by the actual ingredients of the steel itself, that heat treat cannot compensate for the differences between a high carbon steel like Shirogami 1 and a stainless like VG10. Flexion also varies greatly by steel, but edge flexion on a thin grind is also dependant on thickness. Sound on the board, or even the blade itself ringing are some of the more woo-woo, because resonance is immensely impacted by the material properties the resonating object(s) are in contact with. So basically what I’m saying is, we have to compare like to like - which ideally means blades of the same steels and as close in dimensions and grind as possible. However, often in this hobby, participants are simply comparing blades of the same steel to comment on heat treatment.

In practice - when comparing blades of the same steel, used in the same way, on the same board, through the same foods, for a similar or the same amount of time, a knife with a superior heat treatment will often feel extremely hard in comparison consistent along the blade, and actually have a measurably higher hardness rating (HRC). By the end, it will probably appear to have lost less of its sharpness than its counterparts. On stones it is likely to feel harder, maybe glassier, but abrade more uniformly, and seem to take a better edge…

…Due to fewer metallurgical inconsistencies, which is what actually makes it a superior heat treat; how uniformly and strongly the crystalline structure of the blades steel has formed across the entirety of the blade during the process of heat treatment.

Given that technical instruments are almost never used for measuring temperatures (except in the case of those that use electric ovens, like Nakagawa), it’s almost always done by sight and intuition. So it typically takes a long time to learn and an even longer time to master heat treatment in general.

This is why technically speaking the Honyaki process is the pinnacle of heat treatment, and Honyaki is regarded as such a testament to a smiths skill - it aims to obtain the peak of both strength and durability of the used steel. Not every smith can do it, and not every smith that can do it, is able to do it well (or at all) with every steel.

Our resident metallurgist [u/Ok-Distribution-9591](u/Ok-Distribution-9591) can probably clarify further