Taran'atar ends up with a lot of these. A good one is his chapter-long fight with a Hirogen Alpha in Demons of Air and Darkness. The Hirogen is suitably impressed (briefly...) when his supposed victory is turned to defeat by a heavily wounded Taran'atar. Even the aftermath in the next novel adds to the awesome, when Taran'atar demands to be "liberated" from the infirmary as if he somehow wasn't half-dead.
The Reveal in Abyss is another CMOA from the character: "my name is Taran'atar".
Vedek Yevir, of all people, probably has a CMOA for his actions in ''Worlds of Deep Space 9: Cardassia". He helps talk down a 14-year old would-be suicide bomber with his appeal to faith, while he himself is one of the child's hostages. Maybe he is worthy of being Kai after all...
Kira's method of destroying the parasite spawnmother in Unity. She exposes it to all nine of the Orbs of the Prophets, dragging the creature into the realm of the Celestial Temple. Ben Sisko, still a Prophet, then sends it into a timeless void, telling it that by trying to conquer Bajor "you picked the wrong planet."
...and then the displaced Jem'Hadar from "Sacrifice of Angels" are set loose on it.
Corbin Entek's response to Iliana Ghemor in ''Fearful Symmetry", when she angrily tells him he knows nothing about her. His reply is a Long List of observations and details that entirely and casually deconstruct Iliana's entire character.
Rugal Pa'Dar's stubborn refusal to die or give in to despair during the sometimes-terrifying events of The Never-Ending Sacrifice deserve a general mention here. As for more specific examples:
Escaping Ogyas III.
Taking care of Hulya on Ithic and becoming her de facto (and later, de jure) father.
Successfully petitioning to become a Federation citizen.
Ezri demanding that Sirella show her the respect that she is due as a member of the House of Martok.