Interesting imagery here. I really like that line the opening stanza and the idea of an ornamental moon.

Part of me wants to read that as a description of the physical moon in the sky, and part of me wants to read it as a description of the poem’s speaker being just an accompaniment in the night for someone. The last stanza sort of supports this reading, but also makes it hard to carry all the way to the end.

In the beginning of the stanza his arm just hooks on my neck seems to say the speaker could be just an ornament, but the following line suggests that his arm is the moon, so … I don’t know.

Maybe he is the ornamental moon.