Using Deacon Dulas' definition from yesterday, the Old Testament reference to Christ in the antiphon is "Adonai" and the promise or blessing is that God would "redeem us."
When you apply this criteria to the hymn verse, "Lord of might" is the Old Testament reference to Christ, omits the promise or blessing is missing. Each of the hymn verses uses only the Old Testament description without asking for the promise or blessing.
Another unique feature of the hymn is that they are not ordered in the same way as the O Antiphons.
The Service of "O" Antiphons uses the prose text of the antiphon, the correlating hymn text and the appropriate reading from Scripture or the inter-testamental books. Also, a short message can be preached about each antiphon.
Listen to the "O" Antiphons each day between now and December 23 at lutherantimeout.org.
Keep an eye out here at All for Hymn for Deacon Dulas' expositions on the O Antiphons.