Historically speaking the only "Samurai" who ever fought with two weapons was Miyamato Musashi who was more of a traveling duelist than a Samurai (in that he never really served a lord and also never bathed... making it very unlikely he was even recognized as part of the nobility). He maintains a popular influence over Japaneses popular culture references to Samurai because he went his entire life undefeated (though he stopped fighting with metal swords rather early in his career).

His historic rival was a man named Yagyu Munenori who lived at the exact same time as Musashi though the two of them never fought. Musashi lived a ronin's life and challenged countless people to duals defeating each of them in turn while Munenori served as an adviser and teacher to his lord and only fought one time in his life (killing seven men either while or shortly after standing while in his mid 40s).

Their thoughts and teachings were recorded in two of the more famous books about Japaneses swordplay and bushido:

Miyamato Musashi's Book of the Five Rings (orriginally book of the five scrolls).
Yagyu Munenori's "The life giving Sword".

Musashi suggested a number of tactics and tricks to avoid letting the other person get the upper hand and talked about a number of very aggressive tactics. He advocated never giving the enemy room for rest and never turning your back on any enemy but a corpse (and even then only a disarmed one).

Munenori's teachings were more philosophical in nature but they stemmed more from patients and tactical understanding. His final school of sword play was more about turning one's opponent's energies against them than in matching them blow for blow. A master of the Yagyu school should be able to kill an opponent using the opponent's sword (because once you truely master the sword, any sword on the field of war is your sword).

I see both of these schools working better as Prestige classes since they were very unique cases.

Musashi's adepts would likely favor two weapon fighting (if actually emulating Musashi then using a Katana in each hand with a single wakasashi in reserve) and most of the stone dragon stances and maneuvers would work here. They'd be aggressive, hard to move, and cunning.

Munenori's adepts would likely favor defensive styles not unlike the duelist with access to white raven (if emulating the real Munenori) or setting sun (but only at later tiers of mastery).

The nice thing about your class as you have it set up so far is that you could mostly fill either shoe rather well.

As an alternate capstone I might suggest something that comes from older samurai films instead of more recent potrayals:

Master Duelist: If the Samurai wins initiative they may choose to hold a standard action (as normal) to attack on their opponent's turn with full Iajatsu strike bonus only they may still make a number of attacks as though using the full attack action if they choose not to use a maneuver. If a foe attempts to strike the Samurai while they are holding their action they may make their full attack before the effects of the enemies rolls are applied. The first attack roll made in this fashion is an automatic threat for a critical hit.

Reason: In all of the older samurai films, a battle between two skilled warriors was determined in a single blow (Old OA Iajatsu fluff) but in the films it was always the person who moved first who died.

Though I mentioned setting sun in this post, I don't think that the vast majority of Samurai should get it, historically speaking they were much more war time commanders than martial artists as we currently think of them.