Not many Kendoka pick up this style, in fact there's many not even knowing it's a viable option. The Nito (Two Sworts) style of Keno goes back to the legendary ninja and sword art master Miyamoto Musashi.
While games and media want to make you believe double the swords mean double the fun, it's a very delicate art to use two weapons at once. It requires diligence and determination, and discipline to wield them effectively. The second blade is a short, half the length. It is used to parry, distract and land a stealthy hit.
Ree picked up the more aggressive Nito style a while after he got deeper into the art of the sword. There's many who dislike the two sword style, call it flashy and unwieldy. Ree can win many a fight this way, regardless. He's a fierce opponent.