You're right about Night Thrasher...
Talisman?
Interesting theory... but:
She was never exposed to his magic. Not before she had the Talisman, anyway. He'd rejected those Old Ways for her whole life. When he embraced them and started using magic, they hadn't seen each other in over ten years (implied).
Her ability to use magic and the Talisman came from being a The Chosen One.
~ Le Messor
"He who falls in love with himself will have no rivals."
~ Benjamin Franklin