Redsight by Meredith Mooring

Korinna has simple priorities: stay on the Navitas, stay out of trouble, and stay alive. She may be a Redseer, a blind priestess with the power to manipulate space-time, but she is the weakest in her Order. Useless and outcast. Or so she has been raised to believe.
As she takes her place as a navigator on an Imperium ship, Korinna's full destiny is revealed to her: blood brimming with magic, she is meant to become a weapon of the Imperium, and pawn for the Order that raised her. But when the ship is attacked by the notorious pirate Aster Haran, Korinna's world is ripped apart.
Aster has a vendetta against the Imperium, and an all-consuming, dark power that drives her to destroy everything in her path. She understands the world in a way Korinna has never imagined, and Korinna is drawn to her against her better judgment.
With the Imperium and the justice-seeking warrior Sahar hot on her heels, Korinna must choose her side, seize her power and fulfil her destiny—or risk imperiling the future of the galaxy, and destroying the fabric of space-time itself.