You've bound an unfortunate spirit in this bone. At your urging, it will spring forth into an entire skeleton and get between you and those who would (justifiably) do you harm.
The Ensorcelled skeleton bone is a combat item in West of Loathing. Using it will summon a skeleton to protect the player. Summons either your little skeletal buddy, your skeletal buddy, or your big skeletal buddy. This will depend on the number of Necromancy skills the player has. Players cannot create more if they already have at least three in their inventory already.