Tri-Blade, known as Cross Sword (クロスソード) in Japan, is a weapon from the series.
The Tri-Blade is a boomerang type weapon. When thrown, it goes above Arthur and moves in a "L" shape before returning to him. This makes it somewhat difficult to use, and as it doesn't cause much damage, it is considered one of the worst weapons in the game, alongside the Torch. Up to two can be present in the screen. It only appears after completing Stage 4.
With the Golden Armor Arthur can also use the Nuclear Magic (大爆裂の魔法). Arthur creates a large energy sphere above him, which split in two blasts that move straight to the left and right.