In 2 Samuel 21:15-22 several Philistine giants are killed by warriors of the Lord (Abishai killed Ishbibenob, 21:17; Sibbechai killed Saph, 21:18; Elhanan killed the brother of Goliath the Gittite, 21:19; Jonathan killed a man with six fingers per hand and six toes per foot, 21:21). All of this occurs under the leadership of King David.
When Israel was under the leadership of Saul, there was no man found within the armies of Israel, except for David the shepherd boy, who would go out to face a Philistine giant (Goliath). However, under the righteous leadership of King David, Israel has become a nation of Davids; Israel becomes a nation of giant-slayers. Under the leadership of King David, Israel kills the enemies of Yahweh.