When I was stationed in the Philippines WAY back in 74-77 when my "Negrito hunting bolo, or my Negrito ninja sword" got dull I just jumped on top of our decorative concrete fence with a small bucket of water, wet down the concrete and began sharpening away. Not the best edges in the world, but hey they did work. The blade steel is nothing more than the leaf spring from some sort of vehicle. Does not hold the best edges, but sharpens back up (ok, sort of sharp for at the least the first two whacks or two) pretty easily, and I still LOVE that Bolo, actually a 9 1/2 inch bowie blade.