Shusui

One Of the 21 O Wazamono or '21 Great Edges' of the world. It was the meitou of the Samurai Ryuuma, who appeared as an zombie on Thriller Bark that had been given Brook's shadow. Zoro took the sword from Ryuuma after he defeated him. It is designed to increase the damage potential of the user, but Zoro has commented that Shuusui's greatest attribute is its hardness; saying that even if a dinosaur were to step on it the blade wouldn't bend.

While it deals a heavy blow and is extremely hard, Shuusui has a few major problems of its own. Just as Sandai Kitetsu turned out to be a "problem child", Zoro describes Shuusui as having a "temper". However, while its temper is a cause for alarm, Zoro soon discovered the real problem about this blade during his fight with Oz. While Yubashiri was extremely light, Shuusui is quite the opposite and is very heavy.