7 Crazy Harry Potter Fan Theories (That Are Totally Believable)
2. Neville Was Using The Wrong Wand
Neville Longbottom was the boy who went from being outdone by some Cornish Pixies to chopping the head off a giant snake with the sword of Godric Gryffindor. But what on earth happened to Neville that turned him into the ultimate badass that we saw in The Deathly Hallows? After all, this is the same wizard who we see struggling with a simple disarming spell in Order of the Phoenix.
Some fans believe they have uncovered the reason why Neville was so useless for the first 5 films ... his wand. As Mr Olivander says in the very first novel "The wand chooses the wizard" meaning just because you are in possession of a wand does not mean it will work for you. We see as much with Voldemort when he is not able to show his power with the Elder wand because he is not it's true owner.
Neville of course chose to adopt his father's wand who was incapable of using after being tortured to insanity. In other words, Neville chose the wand rather than letting the wand choose him, so he was never able to demonstrate his true potential.
Well, not until that wand was broken in the battle of the ministry, after which Neville gets a new wand. Which would explain why he becomes a much more competent Wizard after the fifth film.