Eugene fighting the plant area boss immediately after the Transition. Not only is he unshaken, he keeps his soldiers in line with the force of his personality. Then he kills the boss while grievously injured.
Kino's quick thinking in York. After Caramela is exposed as an "elf", the city guards close in and ready for some purification. Kino jumps into action by creating a trail of gunpower at the docks and it makes this huge explosion. The civilians go nuts and overrun the city guard. This is the distraction Kino uses to get himself and Millia to safety. What's more impressive is that he noticed the gunpowder earlier while walking down the street and filed away incase it was necessary.
Asuna when she kills two dragons and she does it with just her sword. She doesn't know how to use magic or even her wings.
Just when they finally seem to be home free, Dunwell shows up to block their path. Cue a team attack from Caramella and Asuna to punch a hole through him, complete with Asuna finally getting her wings to work properly for the first time.
Operation Dunkirk hangs on having accurate, up-to-date intelligence on the rebel force's disposition, but the royals have none. Cue Guiche reciting a whole litany of info. Turns out he though it could be important.
Karin, using her signature spell, completely obliterates two battleships and a frigate while heavily damaging two more battleships and swatting four Dragon Knights out of the sky. Then, for an encore, it knocks the rest of the enemy fleet out of formation so it can't defend itself against the incoming Tristanian fleet. Heavy Wind indeed.
In fact, between them, Karin and Morgiana display so much awesome at Dunkirk that Eugene duplicating Asuna's feat of two solo dragon kills in a single battle can easily be missed.
During the debates, just when it seems as though Ryo is about to turn the whole thing into a personal soapbox for his half-baked demagoguery. Sakuya simply stands up, asks him what he wants and undermines his lone source of leverage by promising elections.
Regin showing off his right cross in order to shut Ryo up.
Sakuya expertly handling the arrest of Ryo and the ABC guild on Vadalism charges while telling Lord Justice Richmond to mind his own business. Followed by Henrietta doing the same. In doing so, they both foil Richmond's attempt to use the incident as a pretext to meddle in Fae affairs.
Morgiana's Assassin duel with Rip Jack in the second arc
Midori and Guiche's entire pursuit of Clone Mortimer in the end of the second arc.
Louise going all out and casting Fae Magic. in the second arc.
The whole pursuit is made of gut-wrenching suspense and 100% pure awesomesauce.
The Assault on La Forace Prison
HalO v2.0 Chapter 12. Specifically:
Kirito's fight with Cerberus
Karin duking it out with six triangle mages and Heathcliff