The eventual victory of Toranaga. It is difficult to summarise in a few sentences, given that the whole Doorstopper book is a Gambit Pileup, but suffice to say it is absolutely glorious.
All of Toranaga's plans count as this, whether it's his escape from Osaka, his excellent game of Xanatos Speed Chess when he realises that Yabu has him at a huge disadvantage and his only chance is to bullshit his way through it, or his totally convincing faked defeat, if there is a situation where some truly awesome scheming is required, Toranaga always does well.
Toranaga is also one of the few characters who can make a You Have Outlived Your Usefulness awesome rather than a petty Kick the Dog moment. The offhandedness with which he sentences his treacherous ally Yabu to commit seppuku is extremely satisfying, if only because the victim was a really annoying Smug Snake.
Pilot-Major John Blackthorne:
He has one whenever he manages to pull off a particularly difficult nautical manoeuvre, because even though it's a regular occurrence for him, it is repeatedly stated that there are only a few pilots in the entire world at that time who are equal to his skill. A stand out example of this is during the escape from Osaka, which is a Moment of Awesome for both him and Rodrigues.
His faking insanity to distract Ishido from Toranaga being disguised as a woman during the escape from Osaka at great personal risk is treated as one in-universe by the other characters. As is his valiant attempt to hold off the ninja attack.
Managing to hold his own amongst all his enemies at Osaka. Considering how instrumental he was in Toranaga's escape even his enemies are impressed that he is able to hold his head high when he has to return.
However, perhaps his greatest one is his attempt at seppuku, which is when he fully earns his place among the samurai. Not only that, but he actually manages to stand up and walk after it, which is considered exceptionally strong even by samurai standards.
For even more awesome context: Blackthorne was told that he was to learn Japanese language and customs within a set time frame. If he did not, then every man, woman, and child in the village would be held responsible for his shortcomings, and Yabu would have them crucified. Blackthorne then stated that if this happened, he would not be able to live with the shame, and threatened seppuku. At first Yabu dismisses this threat as empty... but soon realizes that if anything happened to Blackthorne, Toranaga would hold HIM responsible for it. When Yabu doesn't back down, Blackthorn stabs himself, and Omi just barely manages to wrestle the blade away from him. Yabu then relents and states that "Whatever you learn will be fine."
And then there's his "revolution" debate with Toranaga. Blackthorne tries to explain a scenario in which rebellion is justified. But Toranaga states that there ARE no mitigating circumstances when overthrowing one's sovereign lord.
Blackthorne: "... unless you WIN."
Toranaga: "Ha ha ha! Yes, Mister Foreigner with the Impossible Name. You name the ONE mitigating factor."
Whenever she plays around the Yamato Nadeshiko expectations, proving that to be a true YN you must be both very classyandplucky as fuck and showing just how strong she is. Stand out examples include her fighting alongside the men during the escape from Osaka, telling Toranaga to his face that he has to become Shogun (which has been something of a Berserk Button for him), playing Yabu like a harp whenever she has to deal with him, and being completely untouched by her drunken husband's explosive temper.
The end of chapter one for Headman Mura. Facing a man twice his size and capable of the stuff mentioned above being pissy about taking a bath, Mura instantly paralyzes him with two well-timed jabs and forcibly bathes him. And then he, his mother, and his wife take turns discussing the size of Blackthorne's erection. Near the book's end Toranaga's inner monologue reveals Mura has been his spy the whole time.
Mariko's last letter to Blackthorne, and the dream it inspires.
Buntaro shooting four arrows at a target he can't even see, all of them hitting dead on after passing through the same hole in the house's paper door. While drunk off his ass. Blackthorne, who really doesn't like the guy, immediately gives an order that the arrows are not to be removed, as a testament to his skill.
Dirk's Magnificent Bastard tendencies are never more obvious than in his efforts to buy the knoll. Dirk wants it for his headquarters, and as it's a matter of face, will pay anything for it. Brock knows this and plans to drive the auction bid for it so high the Struans will be ruined if they buy. Realising this, but unwilling to lose face by not getting it, Dirk subtly manipulates Culum (who is in despair over his father's refusal to budge) into giving it to the Church, thus relieving him of trying to bid for it as no-one will go against the House of God and saving face. Even more impressively, Culum never realises he's been puppeted until Dirk tells him.
Dirk preparing to go up against Gorth with a fighting iron (even though someone else beats him to it in the end).
To give context, by this point Dirk hasn't slept in forever due to a combination of caring for Culum (who may have the pox) and waiting up to secure May-May's malaria cure from the Jesuits, and knows he's far too tired to have a chance against Gorth - but goes anyway. When Gorth fails to turn up, Dirk just stretches out and goes to sleep until he arrives - leaving the onlookers, who have no idea about any of this, to gawp in shock at how unconcerned Dirk is.
Dirk publicly paying the Brocks off with a Scrooge McDuck-sized pile of silver. "The Noble House decided to pay cash." Then calmly walking away once the receipt has been tendered, leaving his competitors in awe at his wealth and his worst enemy responsible for a huge pile of silver in an area riddled with pirates.
Culum refusing to become a puppet for either Brock or Cooper-Tillman and ordering Stride Orlov to go aboard Brock's ship and fetch Tess.
Jamie McFay just after Malcolm's death when he confronts Norbert Greyforth and punches him right in the face for insulting Malcolm - then beats the shit out of the larger man in the ensuing brawl.
Yoshi battling and killing Sumomo. Despite her ninja training and having the element of surprise, Yoshi insists on his guards not getting involved, outmaneuvers and eventually decapitates her. Those watching can only marvel that Yoshi is really living up to the original Toranaga's example as a total badass.
Edward Gornt's spectacular game of Xanatos Speed Chess towards the end of the novel, manipulating first Malcolm Struan, then after he dies his mother Tess into the total destruction of his father Morgan Brock and the other Brocks and allowing him to develop Rothwell-Gornt into a powerhouse in its own right. He even gets to marry Angelique, too.
Angelique Richauds progressing over the course of the book from Malcolm's beautiful but naive bride-to-be to a Manipulative Bitch who consistently outmanuevers the book's Western male characters to get what she wants, is poised to marry Edward Gornt and looks set to develop into the Gornt family's version of Hag Struan.
Ian Dunross escaping destruction, securing a lucrative business for the future and forcing Gornt to return the airline to Struans or face ruin.
"Yes Asian One" - the reveal that Roger Crosse is a triple agent and that Sevrin is possibly a trap he created.
Paul Choy managing to at least partially outmaneuver Dunross when he presents the half-coin, not entangling Struan's in anything illegal but securing himself a very rich and powerful future, including creating the first Asian stock market. Even Dunross is impressed.
The whole Whirlwind plan itself is a huge one for Gavallan and the other Western characters, managing to evacuate Iran, taking with them all their helicopters and employees from three separate airbases without the Iranians realising what's going on until it's too late.
Early in the novel we find he was petitioning Abdollah Khan for Azadeh's hand in marriage when a group of assassins sent by his son Hakim attack. Erikki kills all of them despite only being initially armed with his knife and doesn't calm down until he knows Azadeh is safe. The Khan acknowledges how awesome this is when he grants Erikki's request despite loathing him personally.
Hakim's ascent to the Khanhood, and how quickly he turns out to be a Magnificent Bastard on a level exceeding even his father. Special mention must be made of his reaction to Erikki's attack - despite being half-concussed, he quickly outmaneuvers and outbargains Bayazid and gets them to leave in peace.
The Mullah Hussain calmly and effortlessly shutting down Esfandiary and the Minister Ali Kia's attempt to squeeze Starke and the others for bribe money, warning them of charges being brought against them for corruption and leaving them in serious fear for their positions and even lives. Later it's revealed he'd worked out the Whirlwind plan but didn't act against it, as he believed it to be the Will of God.