Edward gets one early on . When Kain's dark side storms into his throne room, Edward not only has already cleared his whole castle to keep his people from harm, but he steadfastly refuses to give in to Kain's demand for the Crystal. A moment later, when Kain's troops rush in, Edward still refuses to bend, and opens up a small box holding a Carnelian Signet; the same item that wiped out Mist earlier in the previous game; and it wipes out the troops. It's a darn shame that Kain kicks his ass right after, but the whole incident shows Edward grew some balls of steel since the first game.
Once you play his tale, it gets one better. He plants a whisperweed in fake-Cecil's throne room, so he can listen in on his plans, and that Carnelian Signet? Cecil gave it to him thinking he'd open it and let it wipe out his own troops.Balls.Of.Steel.
EVEN before that, Harley gets Desert Fever, and Edward travels (WITHOUT his three soldiers) back through the Waterway and the Antlion cave to get her a remedy. BALLS OF STEEL.
Not to mention that if you haven't been running from battle, by the time your party is back together, Edward is likely 5-9 levels higher than your swordsmen, has a turn bar that fills twice as fast, and is stomping everything. With a harp.
Kain overcoming his own dark side in The After Years. While Cecil merely had to take the blows as penance, Kain didn't have the same luck. He has to track down his dark side, which has been beating up his old friends and gathering the crystals, and beat the snot out of it. After the fight, he becomes a Holy Dragoon not by rejecting his dark past, but by accepting it's a part of him, and that he will move on from it.
Again in The After Years, The climax of Palom's tale. 'Nuff said.
Palom: "She may be a lousy epopt, but as my student, she passes with flying colors!"
*Learned Particle Bomb Band!*
Ursula takes on Dark Kain, alone! And at a decent level she can easily hold her own.
Should you so choose, Edge can finally have his one-on-one rematch with Rubicante in the first half of the final dungeon. Not only do you earn some great armor for winning, but can definitely see how much the two have come to respect each other. They definitely would have been friends had they not been enemies.
And before that, you can fight with Edge against Dr. Lugae. Sure, Rubicante may be Edge's Arch-Enemy, but it was Lugae who turned Edge's parents into monsters, and in the original game Edge never got a shot at the guy. Now he can.
Close to the end of the True Moon, you face the Mysterious Girl, with Bahamut under her power. If you did everything right up to that point in re-gathering the Eidolons, Asura and Leviathan plead to him to return to his senses, and he Megaflares them without a word, appearing to be impassive to their pleas. Then, the Girl orders him to kill the party... and he turns around and hits her with Megaflare.
Mysterious Girl:No... No! Bahamut: You dared to believe you had rule over our Eidolons? Mysterious Girl: What? Bahamut: My Eidolons are much more than mere pawns of power! Does the true light reside within you? Bahamut, the Father of all Eidolons, shall deliver your final judgement! Mysterious Girl:R-Reflect... Bahamut:''You waste your breath!''*Megaflare*
Earlier in the True Moon the party confronts The Dark Knight Cecil who berates Cecil for casting him aside. Eventually, he reduces your party to their last legs, and Cecil protects them as he tries to strike them down one by one.
After this Golbez jumps in to save Cecil from a fatal blow, which snaps Cecil out of his Heroic BSOD. If you have the right party instead of dying, Golbez is saved by Rosa and Ceodore, who give the Dark Knight a Shut Up, Hannibal! when he berates them for siding with the man who cast him aside and tried to destroy the world before turning the scale of the Curb-Stomp Battle a full 180.
The new post-game bonus boss in the PSP version is Lost Babil, and has you form three parties to destroy it piece by piece.
What makes it even more awesome is when you think about how it's broken up: Two teams take on the external parts while the third fights the core. It's a re-enactment of the fight against the Giant from the original game, only this time the player is in full control of the entire assault!
It also makes for a nice parallel with Final Fantasy VI, in which you build 3 parties to take three paths through The Very Definitely Final Dungeon, and each group has their own penultimate boss fight each against one of the three members of the Warring Triad before regrouping for the final boss.