Well, for one thing, the ability to do this had to come from somewhere. I'm only aware of a limited number of sources someone could obtain an ability like this.

First of all, the personal demons give out items. But their utility is generally less than this. Furthermore, I'm only aware of one such item per week, and I had this week's item. I used it to make it rain blood on Date Kaname. [wow.]

Otherwise, weekly adventures. Are you aware of any additional source...?