"...phew!"
Ashton let out a huff as he stared at the scene of devastation he caused.
The grenade launcher was still smoking in his grasp, the wild white fire raged in his surroundings, and the agonized cries and looks of terror on the demons' faces were still visible around yet none of this bothered him.
With what he just did, there's no way that any of the demons would survive. They are trapped in purifying flames and the only way for them to get out is by dying miserably.
Some might say that he's overdoing it, and they might be correct. But at the same time, they can't blame Ashton. He's stressed about having to figure out a way to defeat the Demon Prince. He had been thrashed by the thing too many times that he was all out of mercy at this point.
He vented his frustration to this hoard of demons, and it was satisfying as fuck. Therefore, Ashton regretted nothing.