Princess Charlotte, who was raised in a convent and whose most frequently used line up to this point was "Save me, Bob!" picks up a sword for the first time in her life, and engages in a duel to the death with The Dragon (which she wins) while Bob takes on the Big Bad... and dies. Charlotte then avenges him with ease.
This happens to every female character on the show, one by one.
Alice's fluke success in battle makes her overconfident and think she's ready to fight evil full-time. She isn't, and the next fight she's in gets Alice severely wounded.
But when she stiffs him on the bill, his attack is easily dealt with by her genuine hidden combat abilities.
Alice's skills abruptly improve after she heals, with no straightforward explanation.
Parodied: Princess Charlotte goes from damsel in distress to army-destroying warrior whenever she cracks her knuckles.
Zig Zagged: ???
No characters show suddenly improved fighting skills; any Action Girl types are well-established as such from the beginning.
Alice is shown training hard for a number of scenes/episodes beforehand.
"Hey, I dropped a bunch of money on those fencing lessons. Any chance my character Princess Charlotte could, say, use a sword in this movie?" "Okay, Alice, but it will have to be pretty late in the story, we've already got the early scenes storyboarded."
"Alice is turning into The Scrappy because people are sick of seeing her get captured every episode. So how about, next episode, she actually takes down the Monster of the Week on her own?"
Lampshaded: "Since when does Princess Charlotte know how to use a sword? They didn't teach that at the convent!"
Invoked: Not applicable. (Since this trope requires there not to be an In-Universe explanation, it is beyond the control of the characters.)
Exploited: After hearing of Alice's victory over Emperor Evulz, Ethan hires her to help him defeat a Big Bad in another country.