Bonesaw (5e Equipment)
From D&D Wiki
Cost: 15 gp
This saw was often used by doctors to amputate infected and diseased body parts from their patients. You can make a Wisdom medicine check with advantage against the DC of a nonmagical poison or disease. On a success, you end the effects of the poison or disease and one limb of the target is removed.
If you use the bonesaw as a improvised weapon, treat it as a handaxe, but don't add your proficiency bonus to the attack, even if you are proficient with it