“ This mirror has incredible powers. It will power-up any weapon. Do you have anything we can try it on? ”
Unlike other events in the game, this event won't be activated. After the What the Witch Lost... event has been cleared, head outside and go back inside. Talk to her.
She will now give Tomba the Magic Mirror and clear the A Magic Mirror? event. Afterwards, she will show the powers of the mirror by combining the Grapple and the Blackjack into the Grapplejack. The event is cleared.