'Sharpen' in the Bible

but all the Israelites went down to the Philistines, to sharpen every man his plowshare, mattock, axe, and sickle;

If a man doesn't relent, he will sharpen his sword; he has bent and strung his bow.

who sharpen their tongue like a sword, and aim their arrows, deadly words,

If the axe is blunt, and one doesn't sharpen the edge, then he must use more strength; but skill brings success.