Judging from the fact that these human-shaped creatures are filled with a dense Death Aura, it's entirely possible that they used Undead Holy Gold, this special metal, to perform Sacrificial Refinement on an Emperor Weapon.
Undead Holy Gold is not a naturally produced metal, but can only be formed in extremely特殊environments, and is incomparably rare.
It's said that Undead Holy Gold is formed when Death Aura first liquefies and then solidifies, and only after hundreds of millions of years can it finally take shape.
If an entire Ancient Star of Life dies out, there might be a certain chance for Undead Holy Gold to form, but it's by no means guaranteed; even the slightest deviation in the process makes its formation impossible.
You could say Undead Holy Gold is even more precious than Sun God Gold and Dark Immortal Gold.
