An explanation of the strategy for the Archangel Azraflail boss fight.
Azraflail is only vulnerable to damage after dropping the spiked ball. You can use your shield to block the ball and make Azraflail drop it. Eventually, Azraflail will throw the ball without spinning it, leaving you free to attack. After you defeat Azraflail, you can take the heart to increase your fortitude. You will get Corrupted Memory #0.