How does Holly's lack of magic hurt her mission?

Holly has trouble with her old wings; they will not start right away and they don't have much power. This alone will hurt her later because she won't be able to use them to escape the troll after her shield does not work. She switches on her shield which takes a lot of energy from her and makes her sweat. She finds the troll but he is able to see her because of her lack of power. The troll throws a table at her, which catches her backpack and sends her gas tank into the air causing a fire. Holly is eventually able to subdue the troll and put a spell on the humans, but the mess has already been made because of her lack of powers.