Skin is wonderful stuff, but it's not meant to stand up to sharp objects shoved into it with all the force you get from three hours a day of bench presses in the yard. Almost any point will do; wood will go through skin and bone easy enough, so you don't really need metal. A spike through the heart will kill a vampire, but it'll also kill your cousin Dwayne if he objects to a new career as bitch of D Block or can't pay for that gram of H he ordered through the Mexican Mafia.
The problem with knives in this era is lethality. I'm not talking about any fundamental flaw with edged weapons here. No doubt, a knife can kill you as well as a bullet-or could, before antibiotics. That's the problem. One-hundred years ago, if you got gut-stabbed you'd have a very hard time getting a life insurance policy. Say you were some dashing gentleman who offended some other dashing idiot, grabbed his favorite prostitute off him or whatever, and you had a duel. Even if he only got in one belly thrust before your seconds called a halt, which they usually did very fast once claret was poured, you were gone. Once that knife or sword sliced into the peritoneum, it would pierce your intestines and spray a lot of shit, literally, through the bowel. Mother Nature would take it from there, turning your belly into a wonderful 3-D garden of E. Coli, not to mention F through Z coli. You'd rot before you died, and leave a stinky unbeautiful corpse.
Along comes penicillin and the whole game changes. Now they can clean you out, stop the bacteria from doing their thing, and sew you up so you've got a cool scar to show chicks. In fact, I'm wondering why dueling went out of style when it would be totally safe these days. Just proof we're no good no more, I guess.
What this means in terms of edged weapons is you need an instant kill. Bullets can kill by shock alone. I don't mean surprise, I mean shock in medical terms, total shutdown, blood pooling, respiratory collapse. That's because bullets pancake, so it's like you've been slammed with a piston. Edged weapons don't do that. That's why all those old heroes really could fight on with arrows stuck all through them: they didn't even know they'd been shot, those sharp arrowheads went in so smooth and easy. Unless the arrow cut an artery, they'd have to wait days to die of gangrene or peritonitis. And now, of course, they won't die of either. They'll be sitting in the prison infirmary talking their little snitch heads off while you sit in the shithole with another 10 years on your sentence. Big props for you with NF, AB, Crips or whoever, but the rest of it isn't so good.
Shanks for nothing: Simple, timeless, deadly
Which is why you have to stab your target something like 50 times in the gut, so you're sure you've done enough damage to guarantee bleedout, or stab him through the skull. And that's where craftsmanship pays off: if you go for the head stab, you'd better have put in the time with that shank. Shoddy workmanship will leave you ashamed in front of all your friends, your target showing off a harmless scalp wound and your yard boss will probably cross your name off the list for promotion. A terrible situation for all concerned, except the dude who didn't die, of course. Your other option, and it's tricky, is to cut a major vessel. They're there, not just in the neck but in the arms and legs. Take the femoral artery in the thigh, an excellent choice, pumping a huge volume of blood down to your getaway sticks. Even a good kick to the Fem can disable a man, and one slice will pour his career prospects into the cell drain faster than any IV can replace them.
But here again, you're limited by your craftsmanship.
When you've got a small piece of metal for your spear or knife point, you're likely to settle for a stabbing weapon instead of a slashing blade. And it's not easy to get a good artery puncture with an ice-pick style blade rather than a razor-style cutter. So lots of guys in stir go for the old reliable razor-blade on a toothbrush option. I swear, dental hygiene is the prison killer's best friend, what with toothpaste for Super Glue and toothbrushes for mini-halberd staffs. Again though we're down to craftsmanship: will your razor blade stay on the brush when it hits bone? When your target starts slapping and kicking and screaming?