User blog comment:Jopjopjop/Volume 20 Spoilers/@comment-73.46.6.122-20150727181231/@comment-1359322-20150728145033

I believe it was in one of the data section for the Dragon Magazine thing, it describe Sirzechs as an irregular Devil who inherited both the Bael's POD and Gremory's Magic/Demonic Power talent.