I think this is going into grimdark territory, because I was wondering how practical weapons made from human bones, such as clubs or blades, would be. You can also perhaps make it from animal bones, but that's probably not as spooky.
Bones have been made into weapons. That's not unusual, although a little primitive. They wouldn't be very effective against armor. I imagine that human bones probably aren't the best for it - density and other factors change between animals, so somewhere there's an animal whose bones are optimal for it - but I couldn't tell you which is or why.
There's a Tibetan horn that's traditionally made out of a person's thighbone. It looks and sounds horrible.
Yeah, cavemen came up with the idea of using bones as weapons and a few primitive tribes around the world still do it. Humanity as a whole sort of grew out of it because it wasn't super practical or effective.
I don't think they would be very practical at all, but I have used them in a story or two. And Sampson did kill a bunch of philistines with the jawbone of a donkey in one of the biblical tales, so its been known to come up.
weapons need to maintain strength and durability. Bones are structurally strong, but I doubt that they can hold a sharp edge. Bones also do not have the mass to become an effective club, as compared to an iron club at least.
Also probably once used as a weapon, technology has simply evolved that even a stick with a rock attached to it might be a more effective weapon.
Actually, bones make for a rather practical material from which to make weapons. I have an Inuit oosik club, for example. Extremely dense and heavy bone weapon. I would nÃ²t want to be whacked with that kind of weapon! Or consider that famous battle where Samson slew a thousand Philisitines with an ass's jawbone. That's a pretty sturdy weapon, too!
Human bones are relatively small and useless, but several spring to mind immediately as good sources. The key thing to understand about bone, and especially human bone, is that it is a living substance. It is very strong, but it has its limitations. Fresh bone is best for almost all uses. A bone that's been drying in the desert for a hundred years will be almost useless. The latter will be, well, bone dry and brittle.
First, the femur. Fantastic for a club. It's relatively long, relatively straight and either end can be used. The ends are about the size of a fist and are pretty solid.
Next the tibia. Also fantastic for a club. The proximal end is quite large and pretty solid. Also relatively long and straight.
Next, the scapula. That nice curving, flattish portion. Awesome for a bludgeoning or tearing axe. Thin the leading edge down and cut notches all along the edge. A gruesome tearing weapon, that.
Next, the humerus, radius and ulna. Relatively thin & weak, but also relatively long and straight. The humerus can be used as a club in a pinch. Best thing might be to make shanks of any of these bones. Take a good sized stone and smash off one end --- instant splintery, jagged stabbing nightmare. More refined blades can also be made from these bones. Of course, you're not going to get a super fine edge, but bone can be sharpened pretty well, especially at the point. Serrated edges will add to the nastiness.
Other bones like the lumbar vertebrae & calcaneus can be made into a flail. Ribs can be honed down and made into gig tines or arrow heads.
Perhaps the most important consideration of all is the psychological warfare. When your side captures some fellows from the other side, you make sure that all the victims can see what's going on as your lads "harvest" the bones and make them into weapons. Leave a half dozen or so to watch your warriors prancing about with their new weapons, then send them on their way. Give em a good chase towards home, so they can tell their own folk how badass your warriors are. Most importantly, they'll know, next time you come around, it'll be their own relatives fighting on your side!