The use of bones as a weapon.
The common variant is using a plain bone as an Improvised Weapon. Similar to Grievous Harm with a Body, except that that involves using a whole body or at least a bodily limb that hasn't yet been reduced to bone. Bonus points if it involves a Stock Femur Bone or is used for Palate Propping.
Another variant is creating a weapon out of bones. This is particularly common in more fantastic settings, where bones of fantastic creatures can be dense enough to be used as material for making weapons or armor. Those who use/create these kinds of weapons tend to be the primitive sort of people, although on occasion there may be rare and powerful weapons made of exceptionally strong bones.
A somewhat less common variant is a superpower to use your own bones to attack others or defend yourself, with a Required Secondary Power to grow bones quickly, usually in a manner similar to Spike Shooter or Spikes of Villainy. Occasionally dips into Body Horror or Lovecraftian Superpower depending on the portrayal. A subset of Master of Your Domain, in this case, with bones.
Generally, this is an especially common weapon option for the Frazetta Man, cavemen of the Hollywood variety and similar primitives, who are often depicted as using large femur bones, implicitly those of their prey, as crude weapons. See also Primitive Clubs, for big sticks and clubs to denote how primitive a being is. This is also a common option for Scary Skeletons, which will either scavenge bones as weapons from their usually morbid surroundings or just pragmatically break off parts of their skeletal anatomies when in need of weapons.
This trope can also overlap with the Sinister Shiv, because bones of certain animals are dangerous enough, due to how small, sharp and sturdy they can be. Making them good stabbing weapons on the fly, although at times depending on the type of bone grabbed they might need to be broken off to create a spiked tip.
Skeletons in the Coat Closet is what happens when you wear bones as armor regularly. See Ballistic Bone for bones launched as Abnormal Ammo.
