Is the Angel of the Lord a Christophany?

1. Many Christian theologians contend that the Angel of the Lord isn't just a theophany but a Christophany in particular (or a theophanic Christophany, to be precise). And that may be the case. However, Trinitarian hermeneutics and Christian messianism don't require that. Moreover, it can be counterproductive when Christian theologians are too insistent on that identification

2. It's not as if Yahweh is the Father and the Angel of the Yahweh the Son. I don't assume that when Yahweh sends the Angel of the Yahweh (or the Angel comes from heaven), that's the Father sending the Son. 

3. Strictly speaking, Yahweh is the Trinity. When I talk about three divine persons in the OT, it's necessary to have separate designations for each to refer to them, and so I use the name Yahweh to distinguish one person from the other two (Yahweh, the Angel of Yahweh, and the Spirit of Yahweh), but that's semantic rather than ontological. It doesn't mean, at a metaphysical level, that one of them is Yahweh while the other two are not. Likewise, the "Spirit of God/Yahweh" doesn't stand in contrast to the nature of Yahweh, as if Yahweh is physical. There's a difference between the ontology of the persons and the semantics of naming. Although the names represent distinct persons, Yahweh is not a particular designation for the Father. 

4. In the case of the Spirit, that designation corresponds to one particular person of the Trinity because the usage is consistent across both Testaments. Likewise, in NT usage, "the Father" and "the Son" are uniform designations for particular persons of the Trinity.

But "Yahweh" is more flexible. Indeed, in NT usage that's typically a title for Jesus, via its LXX equivalent (Kurios). 

5. Many Christian theologians think there's a direct parallel between Yahweh sending the Angel and the Father sending the Son. But not only is that comparison anachronistic, but it's apt to backfire. If you assume that the Father is the default referent of Yahweh/Elohim, then evidence for the OT divine messianism is limited to a handful of prooftexts. 

6. Keep in mind that disproving unitarianism doesn't necessitate correlating the Angel of the Lord with a particular person of the Trinity. To disprove OT unitarianism, it will suffice to show that there's more than one divine person–and not which is which or how the persons and designations matchup. 

7. In addition, it would be extremely misleading for a unitarian God to reveal or manifest himself–in word or deed–as if there's two or three of him while he inveighs against polytheism and idolatry. A unitarian God would be working at cross-purposes with his true nature and corrective agenda if he did that.

8. In many situations it is prudent not to argue for more than you need to to prove your point. If a less ambitious argument will get the job done, that's often better because it has a lower burden of proof.