My rock; to which I flee for refuge, as the Israelites did to their rocks. See Judges 6:2 1 Samuel 13:6. The horn; by which I have both defended myself, and subdued mine enemies. It is a metaphor from those beasts whose strength lies in their horns. The horn is oft put for power, as Psalms 92:10 Amos 6:13, and elsewhere.
Related Commentaries of Psalms 18:2
Psalms 18:2
2 The LORD is my rock, and my fortress, and my deliverer; my God, my strength,a in whom I will trust; my buckler, and the horn of my salvation, and my high tower.