A Commentary, Critical, Practical, and Explanatory on the Old and New Testaments, by Robert Jamieson, A.R. Fausset and David Brown  at sacred-texts.com
gen 49:1PATRIARCHAL BLESSING. (Gen. 49:1-33)
Jacob called unto his sons--It is not to the sayings of the dying saint, so much as of the inspired prophet, that attention is called in this chapter. Under the immediate influence of the Holy Spirit he pronounced his prophetic benediction and described the condition of their respective descendants in the last days, or future times.
gen 49:10JUDAH--A high pre-eminence is destined to this tribe (Num 10:14; Jdg 1:2). Besides the honor of giving name to the Promised Land, David, and a greater than David--the Messiah--sprang from it. Chief among the tribes, "it grew up from a lion's whelp"--that is, a little power--till it became "an old lion"--that is, calm and quiet, yet still formidable. (Gen 49:8-12)
until Shiloh come--Shiloh--this obscure word is variously interpreted to mean "the sent" (Joh 17:3), "the seed" (Isa 11:1), the "peaceable or prosperous one" (Eph 2:14) --that is, the Messiah (Isa 11:10; Rom 15:12); and when He should come, "the tribe of Judah should no longer boast either an independent king or a judge of their own" [CALVIN]. The Jews have been for eighteen centuries without a ruler and without a judge since Shiloh came, and "to Him the gathering of the people has been."
gen 49:14ISSACHAR-- (Gen 49:14-15)
a strong ass couching down between two burdens--that is, it was to be active, patient, given to agricultural labors. It was established in lower Galilee--a "good land," settling down in the midst of the Canaanites, where, for the sake of quiet, they "bowed their shoulder to bear, and became a servant unto tribute."
gen 49:17DAN--though the son of a secondary wife, was to be "as one of the tribes of Israel." (Gen 49:16-18)
a serpent . . . an adder--A serpent, an adder, implies subtlety and stratagem; such was pre-eminently the character of Samson, the most illustrious of its judges.
gen 49:22JOSEPH-- (Gen 49:22-26)
a fruitful bough, &c.--denotes the extraordinary increase of that tribe (compare Num 1:33-35; Jos 17:17; Deu 33:17). The patriarch describes him as attacked by envy, revenge, temptation, ingratitude; yet still, by the grace of God, he triumphed over all opposition, so that he became the sustainer of Israel; and then he proceeds to shower blessings of every kind upon the head of this favorite son. The history of the tribes of Ephraim and Manasseh shows how fully these blessings were realized.
gen 49:27BENJAMIN (Gen 49:27-33)
shall ravin like a wolf--This tribe in its early history spent its energies in petty or inglorious warfare and especially in the violent and unjust contest (Jdg. 19:1-20:48), in which it engaged with the other tribes, when, notwithstanding two victories, it was almost exterminated.
gen 49:28all these are the twelve tribes of Israel--or ancestors. Jacob's prophetic words obviously refer not so much to the sons as to the tribes of Israel.
gen 49:29he charged them--The charge had already been given and solemnly undertaken (Gen 47:31). But in mentioning his wishes now and rehearsing all the circumstances connected with the purchase of Machpelah, he wished to declare, with his latest breath, before all his family, that he died in the same faith as Abraham.
gen 49:33when Jacob had made an end of commanding his sons--It is probable that he was supernaturally strengthened for this last momentous office of the patriarch, and that when the divine afflatus ceased, his exhausted powers giving way, he yielded up the ghost, and was gathered unto his people.