Garion's calling-out of the Child of Darkthe Dark Prophecy itself, while entering the Place Which Is No More, in The Seeress of Kell:
Garion: "It will change, you know. Nothing you do will stop me from believing that. Torak offered to be my father, and now Zandramas offers to be my wife. I rejected Torak, and I reject Zandramas. You cannot lock me into immobility. If I change only one little thing, you've lost. Go stop the tide if you can, and leave me alone to do my work."
Even the Prophecy of Light praises him for it afterwards.
For this troper, Polgara's Moment of Awesome came at the end of Enchanter's End Game. Aldur offers her a deal - to revive Durnik, who she has fallen in love with and who was just murdered in front of her eyes, she must become or live as "[Durnik's] equal". She interprets this as having to give up her powers as a sorceress - and agrees with barely an instant of hesitation. She thinks that she lost her powers, but in fact Durnik's the one who gains them, making him Polgara's equal, but it's still awesome.
Belgarath later heavily implies that he knew that would be the case, because for once he admits to knowing a little bit more about the nature of their 'talent' than his daughter - not that he'd stop her from first enjoying a good wangst-fest. Thus he gets a little MOA from that situation too.
Velvet gets one in the Malloreon when she throws herself at the feet of one of the villains, screaming and begging for her life, then when he looks away she pulls a snake out of the front of her dress and throws it in his face. Awesome.
Silk's epic clash with enemy ninja infiltrator Brill, who's been following them everywhere for three books by that point, is fairly anticlimactic and ends with the ninja getting tossed off the miles-high cliff. It's the banter about it afterwards that definitely qualifies:
Silk: Guess who I just ran into? Our old friend, Brill.
Belgarath: What was he doing here?
Silk: Learning to fly, last time I saw him.
Belgarath: Oh. Was he having any luck with it?
(there is a muffled 'thump' from far below, a brief pause, and then another)
Silk: Does bouncing count?
No love for Belgarion's stopping a small war in Arendia? He not only shames the mob, but scares the crap out of them by creating a freaking thunderstorm and punctuating his dressing-down with lightning bolts. He then goes to the root source of the problem, Mandorallen and Nerina, and literally forces them at BFSpoint to stop wangsting about their situation and get married. Might also double as a Crowning Moment of Funny.
After being a useless bitchy whiny lump for several books, Ce'Nedra finally steps up to the plate in the absence of her husband to-be and convinces every single legion in the Tolnedran Empire to desert and join her army. She then politically allies every other nation on the continent not actively serving the Big Bad into a massive crusade and leads them off thataway. Particularly interesting in that she has absolutely no idea about military strategy, but is willing to let herself be used as a rallying symbol by those who do.
Garion is made of Moments of Awesome in the second series. Among his many, many exploits as The Hero, he stops an impending war between two friendly armies by summoning a hurricane, pretty much singlehandedly obliterates the defenses of a hostile city, and takes There Was A Door to an epic level in Zakath's palace in Rak Hagga. Plus, there's the whole killing a God thing...
There's also the time when he lets it be known that following him might annoy him enough to result in a mile deep trench spanning several miles in either direction.
One from the backstory: The original Gorim. When the Gods made the races of Men, there was one race that remained Godless (partly due to Aldur not taking a race for himself). None of the Gods cared about them, and told them to seek out UL, the Father of the Gods (who hadn't approved of the other Gods deciding to create a planet to be their plaything, and when the Gods created the Monsters forbade them from destroying them), which most of them did (other members split off, eventually becoming the Morindim, Karands, Melcenes, and Dals). During their wanderings, the original Gorim (then a young man) ordered them to stay in one spot, and set out to find UL on his own. He traveled for years, eventually stumbling upon the Spirit of UL on a mountain. UL, of course, wanted nothing to do with Gorim or the Godless Ones. However, Gorim remained on the mountaintop, being fed by the various Monsters as he waited for UL to return and become God of the Godless Ones. UL returned several times, only for Gorim to give a "The Reason You Suck" Speech to Him about how the Godless Ones were suffering and dying without UL to protect and bless them. You read that right: A mere mortal out-waited and gave MULTIPLE The Reason You Suck Speeches to THE FATHER OF THE GODS. But that's not all. When UL finally relented to be the God of Gorim and the Godless Ones, Gorim gave Him ANOTHER "The Reason You Suck" Speech, this time about UL rejecting the Monsters. When UL refused to be God of the Monsters, Gorim YET AGAIN sat down on the mountaintop and waited. Eventually, UL came back, and ordered Gorim to present each and every Monster to Him, so that He could find the beauty in each that Gorim had discovered during his long years waiting for UL, which led to UL seeing for the first time the beauty in the Dragon, the Unicorn, the Chimera, the Dwarf, the Dryad, the Troll, and the other Monsters. So basically, one guy out-waited, insulted, and withstood the wrath of THE FATHER OF THE GODS, and taught HIM the beauty in beings that were considered "mistakes" and "unseemly" by the other Gods. Bad. Ass.
Sadi poisoning one man at a banquet of thousands, not by poisoning the food, but by observing where he sits and coating his spoon with it.
Sadi: I hope he enjoyed the soup. Mine was delicious.
* You forgot the rest of the line, "I really must get the RECIPE."! After watching a man die choking at a banquet. Sadi is a Moment of Awesome!