Yajirobe's katana is a powerful sword that is always seen on Yajirobe's person.
Yajirobe's katana is very sharp. It sliced through not only Vegeta's tail, but Vegeta's Battle Armor as well, which only the strongest energy blasts could pierce through. It is also capable to slicing right through a solid building with little effort. Yajirobe uses the sword at least four times in the anime and manga. The number of yellow diamonds on the sword handle is inconsistent from shot to shot in the anime.
Yajirobe first uses his katana in Dragon Ball to kill King Piccolo's son Cymbal, slicing him in half. He next uses it while fighting an Ice Monster on his way to get the Ultra Divine Water for Goku in an anime filler.
In Dragon Ball Z, Yajirobe's katana plays a major part in the battle against Vegeta, when Yajirobe uses it to cut off Great Ape Vegeta's tail, forcing the Saiyan back into his normal form. Shortly afterwards, Yajirobe used his katana to slice through Vegeta's Battle Armor after Goku had been defeated, to stop Vegeta pulling off Gohan's tail. The sword was later used by Krillin in an attempt to finish Vegeta off, but was stopped by Goku before he could.
When Future Yajirobe is shown to be killed by Future Android 18 in Future Trunks' Alternate Timeline, his sword appears to be broken. This reason is unknown, but this has quite a resemblance as when Android 18 broke Future Trunks' sword; Future Android 18 may have done the same to Yajirobe's sword if he had attacked her with it.
In Dragon Ball: Yo! Son Goku and His Friends Return!, Yajirobe's sword is seen slicing through rubble from a building.
Video game appearances
Yajirobe uses his katana to fight in the Budokai Tenkaichi series and other video games where he appears as a support-type character. In Dragon Ball Z: Battle of Z, Yajirobe's sword is an item that increases melee attack power for one minute.