In the Oosawa manga, Tiltyu makes an early appearance in the Madino arc as the army is facing Jacoban. Sherides in, whips out her Torron tome, and absolutely kicks his ass, then rides off with a smirk as Sigurd, Azel, and Lex look on in surprise.
In games, give Leaf the killing shot against Trabant. An amazing Badass Boast will come in.
Leaf: Trabant, we meet at last... I... I've waited so long for this day to arrive... I've dreamed of killing you with my bare hands, and I've lived to carry it out!!
Some other battle quotes can give goosebumps:
Tinny: (Against Bloom when he's actually killable) You drove my mother to death. Do I have to remind you!?
Tinny: Are you watching, Mother? I'm going to kill Hilda!!!
Again, in the Oosawa manga: chapter 13 is a whole chapter of awesome for Levin, since he graduates to Guile Hero when he and Fury manage to infiltrate Augusty and pave the way for Sigurd's force to go Storming the Castle.
Sylvia gets hers in chapter 34 of the Oosawa manga, via pulling a Sheryl Nome through refusing to give into despair and singing/dancing for the villagers while Levin is in a Hostage Situation, so the people around her will not be depressed and lose faith. She does it fully knowing that they could perfectly kill her for that in the spot. This also paves the way for Fury and Claud getting theirs when they rescue Levin fast and flawlessly.
As hard as it is, it's still insanely satisfying to defeat Julius/Loptyr without Julia and Naga, if only because of the fact that you're killing an ancient Earth Dragon (well, technically just his vessel), without any sort of divine aid. His sheer disbelief about being slain by mere humans is the icing on the cake.
Sigurd, for all his faults, still managed to conquer half the continent with only himself and a small Ragtag Bunch of Misfits for help.
Ced's debut in the Nea Fuyuki manga. Larcei and co. are scouting out Manster from a distance when they see Dragon Knights attacking the town—only for a powerful wind to kill them, with even Larcei's group being able to feel its strength from where they are. When it dies down, you get to see where it's coming from: the fingertips of a lone figure standing calmly on a cliff, aka Ced. In that moment, you know that Ced is one of the most powerful people in Jugdral.
Seliph and Shanan's reunion in Ch. 3 of the Nea Fuyuki manga. Shanan, having just acquired Balmung, suddenly appears to pull a Big Damn Heroes for Seliph, before Seliph immediately proceeds to return the favour. At that point, Shanan realizes that Seliph has grown past the kid who needs his protection, as they then simultaneously wipe out the remaining enemies—as equals, for the first time.