They missed a lot of details, but the Prince and his posse are actually in a bit more trouble than "house arrest" and Lady Aria is such a sweet heart, she becomes a different person after freeing herself from the Princes and his followers, they were basically suffocating her, making her dependent on them, and basically telling her how to live... All as a form of "helping her". Well, anyways she isn't so much the "Saintess" but she is relatively stronger than most of the people in that world, so she does end up helping out with subjugations after she learns a bit more about magic.