It is the only Possession created by and obtained from a mortal, and not forcefully taken from a god.
Grants the user infinite Item energy. Especially useful with the Bow of Apollo's rapid-fire normal shots.
In Daedalus' Workshop, in the left chest hanging from the ceiling in a glass box. To get it, raise the platform by the crank on the right side and point the ballista towards the locked gate. Then go through the portal facing downwards, to get to the second crank, then go back through the portal and fire the ballista.