monado
The Monado is a sword which appears in the game Xenoblade Chronicles. Initially, it appears as a completely rounded red blade with a hollow circle in it, but when activated a portion lifts away and a blade of pure energy appears out of it, and a glow appears in the circle, along with a symbol which changes based on the power in use.
It also makes an appearance in Xenoblade Chronicles X as a pair of hairpins in Lin Lee Koo's hair. It shares a design with the unpowered sword from the first game.