I did a very fast sharpening through higher grits to check that it worked:
I then went back and sharpened more thoroughly through grits 220, 1000, and 4000, using a rust eraser to take all the oxidation off first.
The petty has an interesting (?) steel composition : "The blades are made of Hitachi Aogami Super (AS Carbon steel), an ultimate Hagane refined from Yasugi sand-rons. High carbon steel (1.40 1.50) with Chromium (0.30 0.50) and Tungsten (2.00 2.50) added for extra durability and longer edge retention. This core carbon steel is clad with 420J1 stainless steel to prevent from rusting."
It came out pretty well, very sharp:
I think that the hapstone was very helpful in getting a uniform, very precise angle and edge. I've been free hand sharpening since 2008 or so, and I can tell that this will help keeping the edge uniform and sharp. Setting bevel angle makes sharpening 60/40 angles easier as well, I think.
Suspending a heavy waterstone above a smaller nicer blade is perhaps a questionable practice, and if I was just into knives I would perhaps (though not necessarily) choose a lighter sharpening medium to use with the jig. Perhaps something with more cutting power for hard tool steels than my Naniwa superstones as well
I found that keeping a finger of my off hand on the underside of the blade while sharpening enabled good feedback from how the stone was running on the blade. I rewet the stone manually from a small jar, just flipping it over.
The stones never came off the rod, the mechanism felt secure.