Well that's interesting and not what I was thinking. I have something similar to that, somewhere, haven't used it in so long I'm not sure I could find it.
rainshadow1: "...finishing off my (Custom) knives with gentle pressure on a super fine slack belt.
(Tight, but un-platened 600+ grinder belt.) It put a very mild convex surface on the cutting edge...."
I do the thin convex by hand using 1/2 dozen light passes on #4 of : soft nail polisher
As last step, it can produce razor sharp edges (or better)
Consider a Lansky system for a decent value sharpener that will produce a consistent angle. I hold my own using a stone and steel. If I want a razor edge I reach for the Lansky and leather strop initially then use my steel to refresh until the edge is gone and it’s back to the Lansky or a stone. The Lansky style systems that utilize a heim to guide the rod is a better design I feel as it holds an exact angle vs the slot style the Lansky has that requires a bit more technique to keep exact.
That's a good find. I watched that & a couple other reviews he did, I like them. He manages to get a lot of information in a fairly short amount of time & is pretty creative in how he tests things.