Although given a literary framework by exilic editors, the poem in Deuteronomy 33:6-25 is probably even older than the Song of Moses in the previous chapter. Stephen L. Cook in Reading Deuteronomy puts this poem, the Blessing of Moses, back at the very beginnings of the monarchy. The Levites offering “whole burnt offerings” (v. 10) ended with Solomon’s reign. The diminishing of the tribe of Reuben (v. 6) refers to wars with the Ammonites in the days of Jephthah and Saul. And Cook takes the “foes” of Judah in v. 7 to be the Philistines.
The tribes who get the most lavish blessings are Levi and Joseph. This fits with Cook’s understanding of the roots of Deuteronomy. Those roots lie with the Levites and in the northern kingdom. The blessings are earthy rather than spiritual. The fruitfulness of the land and success in warfare are chief among them.
Yet these are framed by the situation at the time of the exile. So they are open to more spiritual interpretations. So, of instance, Cook sees the warlike language of v. 11 about the Levites tempered by their role as teachers in the previous verses. Perhaps their weapon is now the Torah.
The reference to the incident at Massah and Meribah in v. 8 is interesting. Cook says it changes some of the details from other texts about the incident. Exodus 17:2, 7 say that Israel tested the Lord there. But Deuteronomy 33:8 says God tested Israel (or Levi) there. This agrees with Psalm 81:7–another sign of the common tradition with the Asaph psalms.
In Exodus Moses is the one really under pressure at Meribah. The people are angry with him and want to stone him. But Moses is a Levite, and Deuteronomy sees him as a self-sacrificial model for all Levites.
In regard to another striking verse, I note that Cook says that the mountain in Zebulun/Issachar in v. 19 may refer to there having once been a sanctuary at Mount Tabor.
Deuteronomy 33:28 expresses the longed-for blessed state of Israel as a garden land secluded from enemies. Cook shows how passages in other Deuteronomy-related works like Micah, the Psalms of Asaph, and Jeremiah also express this vision.
As Genesis 49 has the deathbed blessing of the tribes pronounced by Jacob with prophetic overtones, so Deuteronomy 33 has a similar deathbed blessing by Moses. But its position in Deuteronomy after a lot of emphasis upon the curses that befall a disobedient Israel shows that blessing is God’s ultimate desire for his people.