Sforno on Genesis 49:7/ספורנו על בראשית מ״ט:ז׳

1ארור אפם, may their level of anger be reduced, restricted. Yaakov wanted to achieve this by making it harder for them to earn their livelihood, so that they would be fully occupied doing that and caring for their families. They would have to spend their energies by traveling far and wide to secure their livelihood. However, the status of priesthood would remain the domain of the firstborn as it had been before Reuven became guilty of his indiscretion. This status was changed only after the sin of the golden calf when it was transferred en masse to the Levites (some of them). Compare Deuteronomy 10 8, בעת ההיא וגו'.