Ha! Okay, story time! Tell a tale of a time when you felt like you were Crazy Prepared, only to find out you weren't quite Crazy Prepared *enough*.

Never really had that happen... have had the opposite happen though once. Was in a game where we had to abduct a town guard as we were wrongly accused fugitives and we were oddly prepared for it. We had items for non-lethal takedown, rope, handcuffs, a bag big enough to fit a person in, and more. We were all a bit worried at how prepared we were for abducting a town guard.

Not quite. Once we were crazy prepared, but found out that we were even TOO prepared.
It was the end of a short campaign in 3.5 (just four-five sessions), and we had to kill a evil cleric, aka our BBEG. After defeating a dragon and looting his whole hoard, we bought everything that could possibily help to fight a spellcaster, as we all were meelee classes, with chimes of silence, potions, amulets and rings to buff our saving throws, and so more.
We reach his lair, and found out that it was an old tower. We look at each other, especially towards the Warforged Juggernaut and the Ogre War Hulk.
Two seconds later, we were hacking at the base of the tower, brought it down and killed the cleric with the impact to the ground and the following demolition.
Thousands of gold pieces spent for nothing!

Y'know, knowing who she is later in the show, her having this in her fighting style feels really weird.

What do you mean?

No spoilers? She's an action girl, not a seductress.
Spoilers? She's the princess of a desert kingdom currently in the middle of a civil war and is desperate to see no one get hurt because she is a good girl. Doesn't really mesh with this manipulator power set. Kinda why this ability was never even mentioned outside of this arc.

Spoiler replay: To be fair, as she is undercover and doesn't want to be recognized, using a fighting style that is so much unlike your own would be the a pretty clever way to draw attention away from you. no one would suspect that someone who fights so unlike what you are known for might be you, which is probably the reason she only uses this fighting style here and nowhere else in the story. it's because this is the only time she fights as miss valentin, everytime after she's fighting as her true self.

Maybe she learned it for the sole purpose of hiding in Baroque Works? Further distance Miss Wednesday's personality from Vivi?

Spoiler comment: For someone who doesn't want to hurt people, a fighting style focused on hypnotism and non-lethal control makes perfect sense. Better captured than dead, in many cases.

"Foolish Mortals, even now my mighty mech begins it's reign of destruction. Soon this city will be crushed beneath it's feet a mighty death rays. Then the world will-"
SPOT CHECK ROLL! (20)
"Oh... uh... you notice a big important button on the nearby console that reads 'Do not Push!', but it's behind the monolingual villain."
I push the villain into the button! (Rolls a 20)
"... son of a bitch."

Ah, the typical fighter's greatest weakness, will. Which is nuts considering the kinda stuff he does later but I guess it's gonna be from maneuvers and abilities.