Stood before him, i.e. ministered unto him; or (as we use to speak) waited upon him, as that phrase oft signifies; as Deuteronomy 1:38, Deuteronomy 10:8. He became his armour-bearer; he had that place conferred upon him, though we do not read that he ever exercised it; for it seems he was gone back to his father upon some occasion not related, and had abode with him some considerable time before the war described, 1Sa 17, happened.
Related Commentaries of 1 Samuel 16:21
1 Samuel 16:21
21 And David came to Saul, and stood before him: and he loved him greatly; and he became his armourbearer.