The tsaisi, alternatively known as a baton of rank, was a relatively small and slender baton-like weapon utilized by the Yuuzhan Vong species. It was cultivated from the same living organism as the amphistaff. Mastery of a tsaisi demanded considerable expertise and specialized training, thus its use was restricted to the most distinguished officers within the warrior caste, such as the commander named Shedao Shai or the Warmaster Tsavong Lah. Batons of rank saw action throughout the entire Yuuzhan Vong War. The conflict concluded with the Yuuzhan Vong's capitulation, symbolized by Warmaster Nas Choka surrendering his tsaisi to the forces of the Galactic Federation of Free Alliances that had triumphed over his people, marking their defeat.
Tsaisi originated from the same predatory and serpentine species as the more prevalent amphistaff. Yuuzhan Vong warriors employed them as baton-like melee weapons. Distinguished by its reduced size compared to the amphistaff, the tsaisi was a weapon of finesse, requiring specific training for effective use. Given the rigorous training and high skill level necessary to properly wield a baton of rank, they were exclusively used by elite warriors and displayed on the arm as a symbol of status when not actively employed. Typically, they weighed 1.2 kilograms and, when unfurled into a blade, approximated the length of a Yuuzhan Vong's forearm. Beyond its baton configuration, the tsaisi could also transform into a double-bladed dagger, a whip-like lash, or a ranged weapon capable of projecting venom.
Tsaisi were deployed from the initial warrior-led incursions following the failure of the Praetorite Vong until the very end of the Yuuzhan Vong invasion of the galaxy. Commander Shedao Shai carried his baton of rank on his right arm and engaged with it while leading his forces in a ground assault on the planet Ithor. Later in the war, Warmaster Tsavong Lah dueled the Jedi Knight Jaina Solo on Ebaq 9, employing his tsaisi and injuring the Wookiee Jedi Lowbacca when he hurled it like a spear. Lah's successor, Nas Choka, also possessed a tsaisi to signify his position as Warmaster. After the Yuuzhan Vong were ultimately defeated following years of intense conflict, Choka publicly presented his weapon to the Galactic Federation of Free Alliances and surrendered on behalf of his people during a ceremony that took place aboard the Bothan Assault Cruiser Ralroost.
Rank batons were typically wielded by high-ranking individuals within the Yuuzhan Vong warrior caste, figures such as the commander Shedao Shai and Warmasters Tsavong Lah and Nas Choka. Even among warriors, possessing a tsaisi was a rare privilege reserved for the most distinguished. While these weapons were generally limited to warrior officers, the Shamed One Onimi also carried one. This was so unusual that Nom Anor, a member of the intendant caste, expressed shock that Supreme Overlord Shimrra Jamaane permitted him to carry such a weapon. The reality was that Jamaane was merely a figurehead, which explained the unusual privileges granted to Onimi, who was secretly the true power behind the throne.
The Tsaisi made their debut in the 2000 novel The New Jedi Order: Dark Tide I: Onslaught by Michael A. Stackpole. This was the second book in the Star Wars: The New Jedi Order series. They continued to appear regularly throughout the remainder of the series, culminating in The New Jedi Order: The Unifying Force, the final installment.