When Heinald destroyed the demon, all that was left of it was a pitch black triangle-shaped crystal. No energy was emanating from this crystal.
While it felt like an ordinary crystal when he picked it up, it was clear that it wasn't. After all, it was all that was left of a demon!
After he sent it into the dimensional pocket of his robe, he continued walking down the dark road. However, after a while, he sat down and began to meditate to regain his Magical Energy.
At first, he could not put his soul and mind into energy renewal mode due to the uneasiness inside him. However, as time passed, his spirit and mind became more and more calm and he was able to enter a state of energy renewal.
The hours flowed like water.
When Heinald decided that his Magic Energy had been sufficiently regenerated, he continued walking.