Sforno on Genesis 49:25/ספורנו על בראשית מ״ט:כ״ה

1מאל אביך, all of this (assistance) originated from the G’d of your father who had told me that the ascendancy of the Jewish people would manifest itself only after a period of mental suffering and physical debasement. This is what is meant when G’d said to Yaakov in 28,14 והיה זרעך כעפר הארץ, “your seed will be like the dust of the earth,” before he went on to say ופרצת ימה וקדמה, “you will spread out in all directions of the globe.”

2ויעזרך, so that you will not again descend to the depths.

3ואת שדי, same as if the Torah had written ומאת א-ל שדי, “from the G’d whose attribute is Shaddai.” Yaakov mentions this attribute specifically as it had been this attribute of G’d which had appeared to him in 35,11 promising that he would develop into a community of nations. Joseph’s greatness would be orchestrated with the help of this attribute of G’d.

4ויברכך, He, Himself, without intermediary. This would be different from the blessing extended to Ephrayim and Menashe in which Yaakov promised that “the angel,” i.e. the intermediary, who has looked after me would look after these children of Joseph. (48,16). This blessing was also different in character from the blessings of Yitzchok for Esau, and that from Moses for the people crossing into the Holy Land. In all those instances, except in the blessing Moses referred to in Deuteronomy 1,11 which was given by him prior to the sin of the spies, the initiators of the blessing were human beings, i.e. Yitzckok or Moses. G’d would be asked to honour promises made by humans as a blessing. In our situation here, Yaakov commands the blessing to originate with the attribute of G’d known as Shaddai.

5ברכות שמים מעל, in the sense that the days of your life would be completed as planned before you were born. (compare Exodus 23,27)

6ברכות תהום רובצת תחת, material blessings, adequate food and money to buy necessities.

7ברכות שדים ורחם. This is a blessing concerning having healthy and numerous children, in contrast with the expression רחם משכיל ושדים צומקים, “a womb that miscarries and shriveled breasts” (Hosea 9,14)