Shiro no Tempest

From MangaHelpers:

When Princess Diana was born, oracles predicted that her fate was one of destruction and disorder. Despite this, she was a sweet child who spent much of her time caring for the sick at the local monastery. Her father left her alone until her twelfth birthday, but then he sent men, led by the knight Saifar, to have her killed. Diana survived, due to the help of a few loyal friends, including the tomboyish fighter, Attica. Now, Attica and Diana travel together, and their home kingdom has begun the military conquest of neighboring lands. [tethysdust]