I saw the nod a commander gives to underlings, to set plans in action. But he might be simply tilting his head back to look at the heavens, from a vantage point on earth. (It seems odd to me that his vantage point is earth, but if he's got the Second Coming running through his heart, maybe that makes a sort of space/time logic.)
A lot of this eludes me. If it weren't for the final stanza, I would say that the Angel here is actually a human astronomer/astrologer, to whom the shapes in the heavens (the signs of the zodiac) are saying "come and know--". That would presumably make the protagonist of the poem a messenger (the literal meaning of "angel") passing along wisdom from the heavens, perhaps to a ruler who decides war and peace based on that counsel. But I can't reconcile that with the physical, one-on-one personal, Genesis-derived imagery of S3, which certainly seems theological and literally angelic. I dunno. I'll think about it some more.
You don't see the "come and know--" as direct discourse?
I had some more thoughts on "The Elopement" that I stuck in that thread.