What Berachah did Ya'akov bless Yosef?
Rashbam: He blessed him with the standard Berachah of a father to a son.
Seforno: The Torah does not reveal the contents of the Berachah. 1
Ramban: Based on the great love that he harbored Yosef, the Berachah that Ya'akov blessed Yosef's two sons is synonymous with the Berachah that he blessed him. 2
Moshav Zekenim: "Yevarech" in the next verse refers to what came above (Yosef) and below (Es ha'Ne'arim).
What is the significance of the fact that Ya'akov called out to "the G-d of his fathers Avraham and Yitzchak and then to the G-d who sustained him ... "?
Ramban: He was calling to the G-d of his father Avraham (who represented the Midah of Gedulah) and of his grandfather Yitzchak (who represented the Midah of Gevurah, and) who had always sustained 1 him (with the Midah of Emes), to bless Efrayim and Menasheh.
Seforno: He was asking Hashem that the angel that had (constantly) redeemed him (in times of trouble) 2 should bless the boys 3 on the merit of his father and grandfather, who had always gone in His ways.
Why does it say "Asher His'halchu Avosai Lefanav"?
Peninim mi'Shulchan ha'Gra: It is an attribute of Tzadikim - "Shivisi Hashem l'Negdi Tamid" (Rema, Reish Orach Chayim). 1
Ninveh was a great city to Hashem "Mehalech Sheloshes Yamim" - Rosh Chodesh Elul (the first warning), Rosh Hashanah and Yom Kipur. Their initial letters spell Ari - "a lion roared, who will not fear?!"
Why is "ha'Elokim" repeated in the verse?
Moshav Zekenim: Do not say that because Elokim is Midas ha'Din, it is not merciful. Rather, when His children do His will, Midas ha'Din is reversed to Midas ha'Rachamim.