I understand that Voldemort's snake is a powerful one, but why were Hermione and Ron so helpless in the climax of Harry Potter and the Deathly Hallows: Part 2? Hermione was supposed to be the best student of her class and she also knows many spells but when in the climax the snake chases Ron and Hermione, they were about to surrender to the snake before Neville killed it with the sword.
Hermione knows many magic spells, so she can at least do something to save herself and Ron - or at least attempt to do so. Her character was so powerful throughout the movie, but the end felt somewhat odd. Is it because the makers wanted to highlight Neville as another emerging hero?