The Elixir of Healing is an item that he had listed in the shop while making the game. It stimulated the growth cells of the body allowing it to heal any wounds faster.
Unlike the Restoration Elixir, which slowly and gradually heals the wounds without straining the body much, the Elixir of healing puts a great strain and induces extreme pain on the body to swiftly close the wounds.
Due to this, the item was only meant to be used during extreme moments that concerned one's life and death. Even its cost was much higher than the Restoration Elixir which was the better option if one had adequate time to heal.
During his fight with the transformed Jeeves, he had to repeatedly rely on this elixir to heal any injuries he had suffered to continue fighting. The number of healing elixirs he drank during this period of time was higher than counting together all of the other times he had to drink it.
