Symbol of Faith:
You have proven your trustworthiness...
I have a secret to tell you about the demons.
You may find Water Dragon Scales in the Chromatic Highlands. This is a symbol that signified those who long ago followed the Water Dragon, Fafurion. It is an excellent cure for those who have been driven insane by the demons.
Perhaps you can use it on Tears, who was once Parme's best water spirit, but is now a demon henchman. You will find Tears in the Coral Garden.