The Princess of Aelius and the angels' secret

In a world worshipping angels, Jemma Runethorne, daughter of a noble family of the Aelius Empire, has been having recurrent dreams in which a young woman is offered reincarnation from the Angel of Death. When said angel comes to visit her in her family's manor, he triggers her dormant powers and unveils the truth behind her birth. How many more secrets about her origins lie hidden? And why is an ancient archangel so interested in her?