'After making the sacrifice, they will be able to raise an undead army that will lead us to victory.' The King was thinking.
After all the training, dying countless times in the arena, both boys still didn't show any sign of necromancy. But for the King, all that was missing was they sacrificing their soul.
Gremory clearly didn't do it, his heart was obscured by evil but not as the adepts, the adepts have a black heart as if the darkness contaminated a pure heart. Gremory's heart was not contaminated since it was made of pure evil.
For the King, it doesn't matter what they do, if they can raise the undead army in the end. Sacrificing their soul was necessary and the boys were ready for this.
How would they not be? They could be just kids but were prepared to war before learning to walk, receiving the most intensive training for all elements and suffering in the arena every day, their only friend being the pain.
