Only the Philistines could sharpen iron tools. So if the Israelites needed to sharpen their plows, hoes, axes, or sickles, they had to go to the Philistines.
The Philistine blacksmiths charged 1/3 ounce of silver for sharpening plows and hoes and 1/6 ounce of silver for sharpening picks, axes, and the iron tip on ox goads.
Josiah did the same for the towns in the areas of Manasseh, Ephraim, Simeon, and all the way to Naphtali. He did the same for the ruins near all these towns.