The Galaxia is Meta Knight's trademark sword. Its overall shape is flame-like, the blade itself being colored a golden hue, with a ruby on its hilt. Meta Knight has shown to be able to send out sonic booms with this sword as well as utilizing it for more conventional uses, such as slashing and cutting. The name Galaxia first appeared in the Kirby anime. Since then, many games have shown Meta Knight's sword to resemble the one from the anime, indicating that it is the same sword. It was finally proven that Galaxia is the name of his sword in the games in Kirby's Epic Yarn, where there is an item called the "Galaxia Sword" on the Halberd.
In the anime series Kirby: Right Back at Ya!, the Galaxia appears prominently in a back story shown in the episode Crusade for the Blade. In this episode, the Galaxia is shown to be created a long time ago, by the light race of Photron and Meta Knight first used it in defense as Kirisakin tried to steal the sword for eNeMeE. At the end of the episode, Meta Knight is told to be the "chosen one" and thus allowed to keep Galaxia and use it as his personal weapon. Meta Knight is typically seen with the Galaxia, and often uses it in combat.
Sprite from Kirby Quest