She is found in two locations - she appears after the ritual statue is dead in the Releasing the Light quest, and also appears in the final room of the Hoshino Must Die quest.
You feel a gentle presence touch your mind for a moment, and then the spirit before you smiles.
Spirit of Bist'elle tells you, "Thank you for freeing me. Ever since I sealed away my fallen sisters, the Dark Matriarchs have tried to hold my spirit here."
Spirit of Bist'elle tells you, "Forgive my intrusion, but I needed a moment to figure out the language to speak to you in, and I have little time here before this echo of me fades."
Spirit of Bist'elle tells you, "And also forgive my poor gromnies; the darkness that has entered this place has tainted them over the ages. They're growing into something far more twisted and corrupt than their blessed ancestors were."
Spirit of Bist'elle tells you, "I sense the reason why you are here. Tell your employer to seek the Seed of the Morning. It can be found near to where that which is sacred to the Lady of Morning can be found. She will find her path there. What they seek to do, to combat the powers of Darkness that have corrupted love, it can be done. Trust in the Light..."
(Talking to the spirit before timer is up)
Spirit of Bist'elle tells you, "You've returned, and so soon! I might have to start calling you my savior."