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 48:1JOSEPH'S VISIT TO HIS SICK FATHER. (Gen. 48:1-22)
one told Joseph, Behold, thy father is sick--Joseph was hastily sent for, and on this occasion he took with him his two sons.
gen 48:2Israel strengthened himself, and sat upon the bed--In the chamber where a good man lies, edifying and spiritual discourse may be expected.
gen 48:3God Almighty appeared unto me at Luz--The object of Jacob, in thus reverting to the memorable vision at Beth-el [Gen 28:10-15] --one of the great landmarks in his history--was to point out the splendid promises in reserve for his posterity--to engage Joseph's interest and preserve his continued connection with the people of God, rather than with the Egyptians.
gen 48:4Behold, I will make thee fruitful--This is a repetition of the covenant (Gen 28:13-15; Gen 35:12). Whether these words are to be viewed in a limited sense, as pointing to the many centuries during which the Jews were occupiers of the Holy Land, or whether the words bear a wider meaning and intimate that the scattered tribes of Israel are to be reinstated in the land of promise, as their "everlasting possession," are points that have not yet been satisfactorily determined.
gen 48:5thy two sons, Ephraim and Manasseh--It was the intention of the aged patriarch to adopt Joseph's sons as his own, thus giving him a double portion. The reasons for this procedure are stated (Ch1 5:1-2).
are mine--Though their connections might have attached them to Egypt and opened to them brilliant prospects in the land of their nativity, they willingly accepted the adoption (Heb 11:25).
gen 48:9Bring them, I pray thee, unto me, and I will bless them--The apostle (Heb 11:21) selected the blessing of Joseph's son as the chief, because the most comprehensive, instance of the patriarch's faith which his whole history furnishes.
gen 48:13Joseph took them both--The very act of pronouncing the blessing was remarkable, showing that Jacob's bosom was animated by the spirit of prophecy.
gen 48:21Israel said unto Joseph, Behold, I die--The patriarch could speak of death with composure, but he wished to prepare Joseph and the rest of the family for the shock.
but God shall be with you--Jacob, in all probability, was not authorized to speak of their bondage--he dwelt only on the certainty of their restoration to Canaan.
gen 48:22moreover I have given to thee one portion above thy brethren--This was near Shechem (Gen 33:18; Joh 4:5; also Jos 16:1; Jos 20:7). And it is probable that the Amorites, having seized upon it during one of his frequent absences, the patriarch, with the united forces of his tribe, recovered it from them by his sword and his bow.