The best rendering of the passage is perhaps as follows: "But all the Israelites went down to the Philistines to sharpen etc. 1-Samuel 13:21, whenever there was bluntness of edge to their shares and coulters and prong-forks and axes, and to point their goads." Coulters and mattocks were cutting instruments of the type of the share.

But all the Israelites went down to the Philistines - We find from this that they did not grant them as much as Porsenna did to the Romans; he permitted the people to manufacture the implements of husbandry.

But all the Israelites went down to the Philistines,.... Were obliged to go into Palestine, into some one or other of the cities of the Philistines, or to their garrisons, where the trade of a smith was exercised:
to sharpen every man his share, and his coulter; which are the parts of the plough made of iron, with which the earth is cut and thrown up:
and his axe and his mattock; or pick axe; with the one wood is felled and cut, and with the other stones are dug; and each of these for their several uses needed sharpening; and when they did, they were obliged to go to the Philistines to have them done, they having no smiths among them.

Philistines - Not to the land of the Philistines, but to the stations and garrisons which the Philistines retained in several parts of Israel's land, though Samuel's authority had so far over - awed them, that they durst not give the Israelites much disturbance. In these, therefore, the Philistines kept all the smiths; and here they allowed them the exercise of their art for the uses following.