Z-Saber

Z-Saber is Zero's trademark weapon, a green beam saber. It has appeared in every game with Zero with the exception of Mega Man X and Maverick Hunter X, a remake of the former. Almost all of Zero's Special Weapons affect the Z-Saber in some way or allow him to perform a Z-Saber technique.

The Z-Saber is a weapon of many names. In Mega Man X2 and Mega Man X3, it is known as either the Saber, the Beam Saber or the Beam Sabre depending on which versions of the games are played. In Mega Man Legends and Mega Man Legends 2, the Blade Arm is constructed from a varying item and a Zetsabre, which is described as being "wielded by a legendary hero," referring to Zero.

The Z-Saber has been used by X in the past. To obtain the Z-Saber in Mega Man X3, Zero must pass through the one boss door that he can pass through in the entire game. It is found in the second station of Dr. Doppler's fortress, and it's the first door in the level. It leads to a flying bug miniboss, named Mosquitus. Defeat it with Zero, and he will be severely injured. He will pass the Beam Sabre to X before he teleports out, never to be seen afterward. Of course, doing so results in the "bad" ending. To use the Z-Saber here, X or must charge their buster all the way - it does optimal damage and is considered the game's ultimate weapon. In the end of Mega Man X5 and during Mega Man X6, X keeps Zero's Z-Saber. To use it, press the Special Weapon button without one equipped. However, not being experienced with the Z-Saber, X has a rather slow recovery time from slashing. Zero reappears with a new Z-Saber - it is unknown what happened to the original one after this game.

Trivia
The Z-Saber appears as a Battle Chip in the MegaMan Battle Network series

The Z-Saber is presumably the same saber used by Sigma in The original mega man x.