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.
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.