I Samuel 17:51 Therefore David ran, and stood upon the Philistine, and took his sword, and drew it out of the sheath thereof, and slew him, and cut off his head therewith. And when the Philistines saw their champion was dead, they fled.

When you prove the weapons that you have God will give you bigger and better weapons. The weapon will be there when you need it. Amazingly the shepherd had all that he needed to get the job done of killing the giant but after killing the giant God gave him a sword that he uses the rest of his life.

I Samuel 21:9 And the priest said, The sword of Goliath the Philistine, whom thou slewest in the valley of Elah, behold, it is here wrapped in a cloth behind the ephod: if thou wilt take that, take it: for there is no other save that here. And David said, There is none like that; give it me.