In the drowned abbey. Return to the chapel area where you jumped from rafter to rafter. Swim until you find the chapel door with a circle on it, it's below a big platform part, bust it open with the Projectile, follow the stairs, swim through the path, look for another set of spiral stairs, go down them. When you come to a stain glass window with a soul reaver/fire symbol on it, bust that open with your Projectile & continue until you reach a fire........thing, swing your reaver over it to get the fire reaver.