Prosthetic Weapon Arms (5e)

From the introduction:

So, you need a functional artificial arm, and you want it to be weaponized. Most likely, this is the result of an unfortunate run-in with a vorpal weapon, or a critical hit deck your GM bought online from a company with “Kill” or “Genius” in the name. But there are other possibilities. You might have decided a metal arm with a big hook on it is an upgrade in your lifestyle. You might not be satisfied with the limb you got at birth. You might have ticked off the wrong crocodile.