>>491355Find some granite of sufficient size, rub dull metal edge against it properly to sharpen, find another stone with smaller grit, repeat til sharp going smaller grit.
Flint stone axes and knifes, basically you do the same thing to make them in the first place.
If you want something that is still relevant today in sharpness(knife,spear,fishing) get some Obsidian and carefully work that into a blade.
Carefully because it produces ultra sharp surgical edges. Brittle, but SHARP.
