When Arthur went up to see the rank 5 bomb, he saw that it was a spherical ball with runes etched all over its surface and an energy core that was brimming with dangerous power.
Being around the bomb made his skin crawl. He said to himself, "Reminds me of that time Thor brought out a bomb that he called a rank 4 energy core. I guess it is like teacher like disciple. I shouldn't have been surprised by the thought that Sword Flash was making bombs."
This bomb is many times stronger than the energy core that Thor was messing around with. That energy core only had an output of 20D or so. So this rank 5 bomb is 5,000 times stronger than the one Thor had.
This difference in power is why he can feel the threat of death despite possessing power that is above the golden core realm, the same way he had felt the threat of death from Thor's energy core when he was still at the second mortal coil.
