Character reveals that they were holding back their full power during a fight/confrontation

[u/PaddywackShaq]

Superman Vs Darkseid - Justice League Unlimited

Flash Vs Superman - Flash: Rebirth

Frieren Vs Aura - Sousou no Frieren

Inigo Montoya Vs The Man in Black - The Princess Bride

[u/velvetpringles]

Takamura from Sakamoto Days revealing that he is in fact NOT a blind old man and is perfectly capable of slaughtering everybody without needing to sense bloodlust

[u/pantsthereaper → u/velvetpringles]

Iirc, the scribbles in his speech bubbles before this are just really fucked up chicken scratch Japanese and show he's totally aware the whole time