God's blessing would allow the Israelites defeat their enemies (see 24:15–24).
Agag was an Amalekite king whom King Saul defeated (1 Samuel 15:7–9, 32–33). The Amalekites, a desert people, were traditional enemies of the Hebrews (compare Numbers 14:45; Exodus 17:8–16). Agag was probably a traditional title for their king. Since God brought Israel out of Egypt, he fought for them like a warrior and a wild animal (wild ox and lion; Numbers 24:8–9).
Blessed … cursed: See Genesis 12:3; 27:29.