While he may not have acknowledged anyone as his mentor, it's rather silly (thus the name, I suppose) to claim that a mentor is the power he knows not.
He knows WHAT a mentor is. He need not have any acknowledged to have known about it.
Ah well. Keep forgetting to stop taking this seriously.
Author's response
True, but no sillier than thinking love, or a disarming spell, or basic wand-lore was the power, as in canon, and Camilla doesn't state that was THE power, just one of 37 possibilities than didn't entail Harry having to offer himself up to die