User blog comment:B214/High School DxD EX/@comment-27083298-20170415041321/@comment-10330822-20170417025356

Gabriel is the de facto Archangel, because she is the only Great Seraph left after the battle with Trihexa. Whether she actually has the title of Archangel now is sort of irrelevant, because she is the leader of the Throne of Heaven either way. Personally, I don't even think the title Archangel is needed for her, because she is the only Great Seraph, and the Archangel's title only real purpose to show the highest of the Great Seraphs. You could still just call her a Great Seraph, and she'd still be superior to the other Seraph, since she is the only "Great" among them.

Incidentally, was it state anywhere that she was officially "Archangel" now, or is it just being assumed since she is leader? Otherwise, I'm going to assume she's still just a Great Seraph.