I learned a bit about sharpening big knives 40+ years ago in Thailand. I worked with farmers and an old blacksmith. Got a cheap "machete" and a soft sandstone about the size of a brick. In a year or so I had that stone worn down like a swayback horse.
Later I got some better knives, especially the Hill tribe knives. Fairly thick at the spine, beaten out of old truck springs, but fairly flat ground profile with a convex edge. Though they didn't grind them back then. The swayback stone virtually guaranteed a convex edge, LOL.
One time I had a Hmong hill-tribe knife in my pack, maybe a 10" almost Bowie style blade. We had a bad flood and my future mom-in-law was going to butcher a hog. He ex-hubby was going to do it, but asked for a knife. I produced my knife and he laughed at me. I rolled up my sleeve and proceeded to shave the hair of my forearm from elbow to wrist in one stroke. Done deal and the pig was food. Not sure if he was more impressed by the sharpness or because I actually had hairy forearms.
Knife was like this: