I´ve seen many knives like that, here in mexico some people ride around in bicycles with a jig that lifts up the rear wheel and somehow connects it to a grinder (a portable pedal operated grinder) they offer sharpenning services and have a typical whistle call.
When they come around, housewives walk out with their old kitchen knives to have them sharpened, what they get back is a narrower knife with a very toothy edge. Of course they will do pocket knives, they will wear them down in a single session and charge a small fee for doing it.