It's a completely new type of treasure.
After Rosacal's death, you are the person in Boneset Country who felt most 'close' to this treasure, hence it has found its way into your body.
But as for its actual usefulness … you need to figure it out slowly over time. This thing is not a Divine Artifact, nor is it a Magical Instrument, but it does have a hint of the properties of a Postnatal Spirit Item.
This is your opportunity, seize it well."
The Bat Taoist proceeded with caution, "This humble one wishes to give this item to the Master."
Owen Bertram burst into hearty laughter: "Don't underestimate the magnanimity of this official!" The Bat Taoist hurriedly replied, "This humble one was shallow." Bertram continued, "This official can help you analyze the specific use of this treasure, but I tried to probe it just now. This little thing is only close to you and it repels this official. If I were to investigate further, this little thing could cause a ruckus, which may hurt you."
