Albert Barnes Commentary Deuteronomy 33:1

"And this is the blessing, wherewith Moses the man of God blessed the children of Israel before his death." — Deuteronomy 33:1 (ASV)

The title “the man of God” in the Old Testament is one who is favored with direct revelations, but not necessarily an official prophet. The occurrence of the title here is no doubt a token that the Blessing was not, as was the Song, transcribed by Moses himself. Compare (Deuteronomy 31:27).