Quiet bear and Longbow both mentioned sandpaper, wet dry paper, to be specific. It can be found at the local hardware store and local auto-parts store if they carry any kind of touch paint supplies.
Reading your posts, a light bulb went off.
How bout get two sheets of good grade wet-dry (alum oxide) cloth backed paper, 2 different grits, and using contact cement, glue them together back-to-back?
They could be sliced length wise, afterward, and rolled up fairly tight, taped around a flashlite handle, even around a pencil or pen.
Medium ,Coarse, Fine, you name it. Custom make your own 2-sided sharpening paper.
Any merit at all to this idea?? For impromptu "in the bush" sharpening,
of course.