Christ gives the Nephites a passage from Malachi. "Malachi" is "my angel," and the word "messenger" that appears twice in verse 1 is also "malach," "angel." The Father promises to send his angel, to prepare the way. Then the Lord will appear, who is the angel of the covenant.
A couple of observations and a question. Angels are priests, and this is obviously a text of the visionary men about priestly leaders. The Lord is the "angel of the covenant" and the high priest, when dressed and acting in his priestly office, was the Lord. Question: might the Nephites have seen the first angel in Malachi 3:1 as their own Nephi?