Magic Feather/Playing With

Basic Trope: A supposedly magic MacGuffin that ends up being a useless placebo.
 * Straight: Alice is a talented magic user, owing to her powerful magic wand. When the wand breaks, she discovers that she can cast magic anyway - it was with her all along.
 * Exaggerated: Alice is a talented magic user - with an arsenal of nuclear missiles. When she runs out, she realizes that she was nuking people and the missiles were just for show.
 * Justified: Alice needed the confidence, so her mentor told her that the wand was the source of her power.
 * Inverted: Alice always carries an old wand with her, she thinks it's just an useless relic. It turns out it is a powerful weapon.
 * Alice has a nocebo effect.
 * Subverted: It turns out the wand really was the source of her power...
 * Double Subverted: ...however, she became so proficient in magic because of the wand that she ended up not needing it anyway.
 * Parodied: The magical item is a painfully obvious placebo - something like a hairpin.
 * The placebo is a music CD...by Placebo.
 * Deconstructed: The realization that the magic was inside her the whole time strains Alice's relationship with her teammates, as they are unsure if Alice is confident enough to work with them anymore.
 * Alice's mentor gives her a stick, telling her it's a wand. She tries to cast a spell, and can't.
 * Reconstructed: Alice gets over the realization and gains confidence.
 * Like in Cyanide and Happiness, people really like it when they're told that it really was them...when it's on the line of, say, steroids.
 * Zig Zagged: So the wand really is the source of her power...but she gained enough magic experience to not need it...however, that magic power is limited and she needs the wand to cast magic without limits.
 * Averted: Alice knows from the outset that she already has the power inside her.
 * Enforced: "What flaw can we give our hero? ...Lack of confidence, and she has to use a wand when she doesn't need to? Love it!"
 * Lampshaded: "You mean my wand is useless?"
 * Invoked: Alice's mentor, seeing that she lacks confidence, gives her the wand and tells her it's the key to her power.
 * Defied: Alice figures out early on that the wand is just for show, and rejects it.
 * Discussed: "Who's going to bet that if we were to take her wand, it's just going to wind up being some magical 'you didn't need the magical wand and you had the power inside you' thing."
 * Conversed: ???

I know you thought you needed things like sleep or a social life to be a troper, but in reality, those things were just a Magic Feather. The power to edit tropes was with you all along.