More of a funny moment, but when Laura gets thrown across the room by Chifuyu in episode 7 of season 2, she still makes a flawless recovery from it.
In the 7th volume of the novels, when Kanzashi has to take out a target with her IS's missile launcher- which doesn't have its targeting suite installed yet- she manually enters all of the telemetry data for 48 missiles in the middle of combat.
In Volume 8, all remaining doubts about Chifuyu's skill is shattered when she takes on Fang Quake. Without an IS. And defeats it, with nothing but six explosive IS katanas. Granted, it was Yamada who landed the final blow...
The anime version of this scene was... significantly less awesome. See Filming For Easy Dub on Infinite Stratos's main page.
Madoka really shows off her Badass cred in the final episode when we see just how broken her new I.S. Kurokishi is. She swats aside Cecilia like a fly and tanks the combined firepower of Rin, Laura, Charlotte, and Kanzashi all at once. When Cecilia gets back into the fight and unleashes a massive energy burst on her, she takes the hit dead on and is calmly standing in the middle of the fireball when the smoke clears.