User blog comment:Jopjopjop/Volume 19 Spoilers/@comment-16281343-20141224124121/@comment-16281343-20141231192336

Gabriel is the King, Griselda is the Queen.

Although I can't find any info on the skills of Vorpal Sword that can be connected to the current DxD, if ever that name comes up I think Kiba would most likely have it as their is another power-up waiting for him.