Despite possessing 20% of Grimm strength, as what Kyrian had already displayed, it is still not enough to withstand the toll brought upon by the Hell Flames. What truly made the Hell Flames bearable for certain creature is either having a Soul Realm of exquisite quality, true to High Humans and Ranked Beings, or, they have an immortal-like physique such as those that reached the Demigod Class or higher.
The Grand Knights are neither. At least individually they are not. Fortunately, there is a way to accomplish the latter, to attain the Demigod Class physique, though temporarily, through the power of the God King Insignias they bear. However, to utilize that, it will require an extended amount (well, it’s not exactly that extended but being in the present situation, that’s what it will fee
