King Slayer

The King Slayer is a blade craftable only by superior blacksmiths. It is a sword sharp enough to pierce the armor of sub-deities and does a huge amount of damage.

Examples
There have been 3 king slayers in the quadrology. The Hero's Gladius, the Angelic Blade, and the Heavenly Sword. Each were used to fight different final bosses. The Hero's Gladius appears twice while the others appear only once. Each were specially crafted with the intention of slaying a specific overlord, the Gladius being used for Drakus, the Angelic Blade being used for Sukard, and the Heavenly Sword being used for Kraidrus.

Discrepancies
Although it seems like no matter how the damage of the sword changed, the difficulty of the final boss remained the same, it is not at all like this. The Hero's Gladius claims the title of "Best King Slayer" since in FSL2 it dealed 85 damage. You might wonder, the Angelic Blade did 400, and the Heavenly Sword did 800. These numbers are nearly arbitrary because of something called Damage Scaling. If the FSL2 gladius was in FSL3, it would deal 425 damage, if it was in FSL4 it would deal 1020. The Heavenly Sword claims the title of "Worst King Slayer" as if it was in FSL3, it would deal 333.33 damage, and in FSL, 66.66.