Small update - got 2 local knives Shirogorov. One small, Shark model - 80 mm blade, but 4 mm thick, very powerful blade, 440C steel, early release circa 2007-2009. The second Hati Model, it is large - 95mm blade and 4.5mm thick which tapers towards the tip. Both fit very well in the hand. Hati - flipper, opens and closes very quickly, this is a really big knife

I sharpened them on a fine stone. 440C and S30V here are hardened for heavy use, they are not very hard, but it is quite difficult to get chips on the cutting edge. Chris Reeve has a similar approach to hardening steel. It's not for everyone, but it's suitable for most people