(Loved Trope) Character finally reveals their true power level

[u/Tannerknox]

John Wick - the viewer spends the first 25ish minutes just being told John Wick has an infamous past of being an assassin. Once the first home invasion happens, we see him fully unleash the Baba Yaga, completely annihilating a dozen unsuspecting assailants.

Rebel Ridge - the viewer learns early on that Terry Richmond is a Marine veteran who was never sent overseas for an initially unclear reason. Over half-an-hour into the movie he has a standoff with the town’s corrupt police chief. It’s revealed in this scene that he’s THE martial arts instructor for the Marines. He proceeds to disarm two police officers with extreme efficiency.

Naruto - Rock Lee is a character we’ve seen prove to be a capable fighter in a couple of episodes prior to his fight with Gaara, despite Rock not having any inherent Ninjutsu abilities. When his strikes can’t make it through Gaara’s automatic sand shields, Rock’s instructor, Guy, gives Rock permission to take off his leg weights. The bystanders watching the fight don’t understand how taking off some leg weights will give Rock an edge in the fight, but then when Rock drops them, they’re revealed to be hundreds, maybe thousands of pounds. This then reveals that Rock can move at super speed, and he can shockingly out maneuver Gaara’s first layer of shielding.

[u/Mission_Sock2114]

I'd argue the Spiegel fight is the actual scene where Frieren shows her true capabilities, by proxy of the clone at the same time since she barely did anything against Aura.

Your example is the more memorable/impactful one however.

[u/FrtanJohnas → u/Mission_Sock2114]

The Aura "battle" was just there so that Frieren has something to do while Fern and Stark show off their skills and get experience in my opinion.

They tried to hype Aura a lot, but Frieren casually defeats her at every turn. Even when Frieren was fighting Denken she had to engage a lot more.

So Frieren vs Frieren clone is the showing of their true power, and Frieren vs Denken is a second showing of the trole, as immediately after she defeats both Denken and Laufen she destroyed the barrier.

Aura vs Frieren was essentially a filler combat.

[u/Nanocaptain → u/FrtanJohnas]

Aura vs Frieren is there to explore demon's mentallity more and set up the Sages of Destruction for Macht. And by proxy they developed Flamme and Frieren.

Frieren also only had such an easy time against Aura because she could very easily exploit her weakspot. She specifically says that if Aura wasn't so overconfident then she could have really made Frieren sweat by sending her army at her.

Stark and Fern Vs the Lackeys was there for the action. Frieren vs Aura was there for the lore, the sickass reveal and the aura farming in both meanings.

[u/IngloriousTom → u/Nanocaptain]

she could have really made Frieren sweat by sending her army at her

IIRC that's mostly because she took a lot of care defeating the corpses without damaging them.

If she unleashed the same power displayed against dark-frieren, I believe Aura and her army wouldn't stand a chance.

[u/lbrwnie → u/IngloriousTom]

Yeah I don't think Aura could do shit about that black hole spell she whips out in that battle.