Used to work with a guy; a former saw filer. That guy knew how to get things SHARP, and shared what he knew. His weapons of choice were a 6" bastard file and a decent steel. No stones, no fancy angle holders, no diamond anything; just the sharpest knifes I've ever seen.
His EDC was an old 1930's era grocer's pocket knife. Sort of a long bladed, folding predecessor to a box cutter. Ouch! I cut myself just *thinking* about it.