Overheated edge BESS scores

[KnifeGrinders]

Now, with that 2-step sharpening they use, and looking back to the diagram, what may be an explanation for the difference we see?
The grinding is done at 250 RPM with a circulating fluid coolant, and can be ruled out.
We have the felt wheel left.
My sharpening was different in that instead of the felt wheel I used a slotted paper wheel - the slotted wheel cools like a fan.

Asking myself how a felt wheel might cause the quicker edge blunting over the first hour, the only explanation I can think of is the apex overheating.
So I put a finger on his rock-hard felt rotating at 2850 RPM, and got a burn in a fraction of a sec, indicative of 80-90 C.
The steel in these knives is relatively low-carbon, around 0.5% - for them intermediate annealing starts at 260 C.
Watching him honing, he spends on the felt about 2 sec per blade side, alternating sides 4-6 times - around 10 sec overall.
I think some annealing of the apex in the area up to 0.5 micron thick is probable.
0.5 micron or 250 BESS is where the two knives start scoring the same.