The abstract noun "faithfulness" can be translated with anadverb. Possible meanings are 1) "the one who faithfully loves me" or 2) "the one who faithfully protects me." (See: [[rc://en/ta/man/jit/figs-abstractnouns]])
David speaks of Yahweh as if he were a fortress that protects him from attack. Yahweh is the one who protects David from harm. (See: [[rc://en/ta/man/jit/figs-metaphor]])
David speaks of Yahweh as if he were a shield that protects a soldier. Yahweh is the one who protects David from harm. See how this is translated in [Psalms 18:2](../018/002.md). (See: [[rc://en/ta/man/jit/figs-metaphor]])
Going to Yahweh for protection is spoken of as taking refuge in him. Alternate translation: "the one to whom I go so he will protect me" (See: [[rc://en/ta/man/jit/figs-metaphor]])