Rob, this is strange.
What do you use for sharpening?

I have a lot of different knives,
for only 2 knife intervention engine required.
These knives have high-speed steel R6M5 with 63-65 HRc,
USA analog - T11302 or M2, Japan - SKH51.

More I have Buck 102 (blade stamp 72-86),
it is easy to sharpen

sorry for bad photos