1 Samuel 17:50 KJV — So David prevailed over the Philistine with a sling and with a stone, and smote the Philistine, and slew him; but there was no sword in the hand of David.
A sling and a stone and his relationship with God.
That’s all you need to kill the Philistine.
In fact, all you need is the last one.
Everything springs from that.