Nicholas used a spell from Divine Punishment that was slightly weaker; the spell was Righteous Judgment.
There were more than 100,000 complete souls within Nicholas' fallen staff. It would demand more of his equipment and he would need a million more souls in order to use powerful Divine Punishment spells.
Righteous Judgment had a prerequisite of having to be used against genuine heresies. It would be able to cleanse their souls completely and force them to lose their powers of faith. What made it different from a powerful Divine Punishment spells was that the former could only strip the opponent's power of faith and not their combat abilities.
Nevertheless, Nicholas was not involved in a one-on-one fight. There were six other towering elemental stone statue soldiers surrounding the huge light-blue monster.
