It is not his guardian spirit, it is part of his Cloud (Same technique that Alummi uses to summon Anna). Amidamaru also appears, who is petrified, and Sakurai, who is currently in heaven with Chiharu.
As Thorim said, the technique is incomplete. Amidamaru gives him techniques to evade death. Sakurai gives him a battle instinct to sense danger. And Fausto gives him the visualization to treat and heal wounds on his body.
