The strongest three divine artifacts associated with Zeus are the Zeus' Staff, Sea Emperor Trident, and Netherworld King's Saber.
The most powerful Zeus' Staff had been lost long ago. The Sea Emperor Trident has also been lost for over a thousand years.
Now Hercules only has the Netherworld King's Saber, which possesses the Law of Soul Cutting, a very powerful force.
Each use of the Netherworld King's Saber comes at a great cost. Unless absolutely necessary, Hercules would not use the Netherworld King's Saber.
Moreover, the Netherworld King's Saber has great limitations. Hercules can only use it on the Sea Emperor Star. If too far from the Sea Emperor Star, it exceeds the Saber's range.
The Iron Mountain King and the Black Eagle King of the Black Banner Alliance both know the characteristics of the Netherworld King's Saber. They operate at the space nodes of the Sea Emperor Star System and do not approach the Sea Emperor Star.
