He says so himself; he's the most dangerous person they're ever going to meet besides Sauron.
Yeah but this is Lord of the Rings universe... A man with an Uzi would be the most dangerous person in middle earth.
A man with an Uzi would also arguably be the most dangerous person in the Wizarding world.
"You need to chant Abracadabra and wave your wand to kill me? Okay, I can kill you by squeezing one finger a bit. In fact, I can kill a whole crowd of you like that."
The wizards and witches weren't maintaining the masquerade because of some Prime Directive BS, they were doing it out of fear. IIRC they started doing it because they were constantly being killed off by superstitious (and possibly genre savvy) Muggles, and that was back when the best ordinary weapons were bits of sharp metal. In the modern world they have bits of metal (and plastic, and wood) that can accelerate lots of even smaller bits of metal to very high speeds.
If you're going to pull out modern weapons Gandalf would auto-win because he can resurrect if he takes a bullet from 500 meters out and Dumbledore can't. Also, Abracadabra? It only works on living things. Now come at them each with an attack helicopter or a drone strike and see who comes out better. Yeah, not the direction you want to go, not least because it ends with an old man and something that takes the form of an old man being splattered by high explosives, and then possibly the latter showing up a bit later with clean robes.
I'm surprised that nobody mentioned the most useful ability of Gandalf yet.
[Gandalf] raised his hand, and spoke slowly in a clear cold voice. 'Saruman, your staff is broken.' There was a crack, and the staff split asunder in Saruman's hand, and the head of it fell down at Gandalf's feet.
Checkmate, Dumbledore.
Can't Dumbledore cast spells from his hand with no loss of ability or power? unlike Gandalf.
Did you read the quote? Gandalf shattered Saruman's staff by raising his hand and willing it to be so. He fought the Balrog with Glamdring. In fact, the only thing I actually remember Gandalf using his staff to do was the light trick to drive off the Ringwraiths.
The light thing was Peter Jackson interpreting it that way; in the books it's described as a bolt of fire or some such.
GANDALF LAZOR
Plasma. BURN THE HERETICS. Gandalf the Grey Knight. Can't get the thought out now.
Brb writing fanfic
Be sure to share it when you're done.