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, then descends in front of him, goes a little forward, then up again, before returning again to Arthur. 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 Bronze Armor or Golden Armor, it is enhanced into a Shuriken (光輪のクロスソード, "Halo Cross Sword" in Japan), which is slightly faster, but still difficult to use because it will have the same effect of the Cross Sword.
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, striking enemies above Arthur, but not effective for enemies in front or on the back.