Arthur returned home and did not sleep but focused on creating his meditation technique! There was one inside the memories of the Blood Monarch, which he started using some time ago; the 'Ancient Blood Demon Technique' was its name.
He couldn't share such a technique with Delphine or the other members of his cult, as they were incapable of practicing it! That technique was solely for the one with the Blood's Monarch inheritance, so Arthur dismissed the thought of sharing that.
But it could still serve as a base for him to create a new one. What he needed was something with a similar effect to the Dragon Meditation Technique, meaning the users who practiced the technique would also grant power to the creator, which was Arthur.
He wanted to merge the two techniques so that the members of his cult practiced something darker while giving him more power. But, of course, it would work both ways, and Arthur would grant some of his powers to the users, but it would still benefit him.