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.
Related Commentaries of 1 Samuel 13:20
1 Samuel 13:20-21
20 But all the Israelites went down to the Philistines, to sharpen every man his share, and his coulter, and his axe, and his mattock.
21 Yet they had a filef for the mattocks, and for the coulters, and for the forks, and for the axes, and to sharpen the goads.