Commentary for Genesis 48:10

לא יוכל לראות, he could not see clearly. In order for a blessing to take hold it is necessary for the one bestowing the blessing to see the party whom he blesses at the time the blessing is pronounced. [the same is true of a curse, this is why Balak took Bileam to a vantage point from which he could see the people of Israel whom he had been hired to curse, clearly. (Numbers 23,13). G’d also took Moses to a point from which he could see the land of Israel clearly so that he could bless the land. Something similar occurred in Kings II 2,24 where Elisha turned around to face the lads mocking his baldness before he cursed them.

ועיני ישראל כבדו מזקן, Israel's eyes were heavy with old age, etc. Why did the Torah choose this point to inform us of Jacob's failing eyesight? What does it have to do with his proceeding to embrace and kiss Joseph's children? Besides, why did the Torah have to describe these kisses as להם instead of אותם? Perhaps one of these details will help us understand the other detail. Jacob embraced the children in the wrong places and kissed them in the wrong places due to his failing eyesight. If that were true the expression להם instead of אותם is quite understandable.

ויגש אותם אליו, not in this order.

וישק להם ויחבק להם, “he kissed and embraced them.” Man is not blessed with the presence of the Divine (spirit) unless he is in a state of joy, happiness. This is why being kissed and embraced by his father enabled the blessing to take hold on Joseph and his sons.

וישק להם ויחבק להם, the physical contact was designed to make Yaakov more attached to them so that his blessing would be correspondingly more effective.