Isaac’s words…are fulfilled in Christ and in those who are justified through faith, who are also made sons according to the promise in Isaac.
The words of the blessing, I believe, signify the sweetness of the spiritual perfume in Christ, like that of a garden or a plentiful field spreading a sweet and beautiful perfume from its spring flowers.
And so Christ described himself to us in the Song of Songs: I am a flower of the field, the lily of the valleys.
He was actually a lily and a rose born of the earth for the sake of humanity. Since he did not know sin, he was the most divine of all those who inhabited the whole world and produced a perfume through his works.
For this reason Scripture compares Christ with a field blessed by God, and with very good reason, because he is the perfume of the knowledge of God the Father.
As the divine Paul says, But thanks be to God, who in Christ always leads us in triumphal procession, and through us spreads in every place the fragrance that comes from knowing him.
These things therefore fit with Christ and also fit quite reasonably with the new people: May God give you of the dew of heaven and of the fatness of the earth and plenty of grain and wine.
The dew of heaven and the fatness of the earth is the Word, was given to us by the Father, together with the participation through the Spirit, and therefore we were made sharers in the divine nature through him.
And we also received plenty of grain and wine, that is, strength and happiness. In fact, it is said truly, Bread strengthens the heart of man, and wine makes glad his heart.
Bread is the symbol of spiritual strength, wine of the physical. They are given to those who are in Christ through him.
How else are we made stable and firm in piety and immovable and aware to think the right things?
Afterward the power of blessing is transferred again to the Emmanuel himself. And let nations serve you, and princes bow down to you, and be lord of your brother.
The Emmanuel was called the firstborn when he became so with reference to us, among many brothers. But for this reason we must not forget that he is God and Lord of the universe.
We worship him as God, and he has reigned as God over those who were called from the brothers through grace. Who in the heavens shall be compared to the Lord among the sons of God?
[...] This is the blessing of Jacob, whose strength refers to the Emmanuel himself and to those who are justified in the faith.
Cyril of Alexandria (c. 376-444): Glaphyrorum in Genesim, 3.5 (PG 69.172-173); ACC 2 (2002) tr. Sheridan; from the Monastic Office of Vigils, Sunday of the 4th Week of Ordinary Time, Year 2.