Space Sword Blaster was an offensive attack used by Sailor Uranus.
When this attack was used in the anime or the video games, the Space Sword's blade would glow, and she would then swing the Sword and release a wave of energy that would destroy its target. In episode 169, it was demonstrated that this attack could also hit multiple enemies simultaneously.
When it was used in the manga, the blade would grow larger and glow, and she would then use the Sword to physically attack her enemy.
Space Sword Blaster involves Sailor Uranus raising the sword in the air, creating a singe orange orb with a ring around it then when she lowers the sword, the one orb turns into many, and then take on a crescent shape, hitting many targets.
Sailor Uranus used this move in Sailor Moon SuperS: Zenin Sanka!! Shuyaku Soudatsusen. Sailor Uranus made a slash in the air with the sword and sent a wave of energy at the target.
This is, also, one of her two attacks in Sailor Moon: Another Story (the other being World Shaking ). She swings her sword, releasing a flash of energy that damages the target. It hits one enemy at a time and consumes 4 EP.
The literal meanings of the kanji characters used in the name of this attack in the manga are "space" (宇宙), "sword" (剣), and "turbulent wind" (乱風).
The Space Sword is actually based on one of the Three Sacred Treasures of Japan, the Kusanagi. The sword was said to represent valor. Interestingly enough, this real life sword was said to have the power to control the wind which so happens to be Sailor Uranus' ruling element and suggests that those energy blasts that fire out of the sword during the attack could in fact be some kind of wind energy attack.
In the cloverway dub It was referred to as a saber.