A flat mirror will not work for me, since the angle of incidence is complementary to the angle of reflection, which means that bad energy is actually diverted from the sender and bounced onto innocent parties. My mirror looks like a waffle, and is optically designed to send stuff back exactly where it came from. It's also semi-permeable, and that is even harder to explain. I guess Younger Self is not altogether consistent. On the issue of choosing between the two modes.
Justice is a tautology.
It protects and maintains, but does not allow for growth. At the beginning, the women of the tribe have a ritual opportunity to make a wish for the coming year. But the heroine does something even better. Had she chosen, she could not possibly have received anything more than she was capable of imagining. Taking the risk of not choosing was opening herself to surprise and transformation.