Generally, if you can’t get an edge to refine as you move to smaller-sized abrasive, that’s an issue with temper. Literally, the steel is too brittle and won’t support refinement beyond that point.

Except that stropping makes it sharper, though! This points towards ductile steel forming a burr, rather than brittle steel chipping when refined, no?

I’ll explore both directions, starting with thinking about better burr removal