1 Kings 22:11

And Zedekiah the son of Chenaanah made him horns of iron
Horns are emblems of power and might, and iron ones of greater strength still; the prophets sometimes made use of visible signs, to represent the things they prophesied of should come to pass, see ( Isaiah 20:2 Isaiah 20:3 ) ( Jeremiah 27:2 ) , and the same method this prophet took:

and he saith, thus saith the Lord; imitating the true prophets: with
these shall thou push the Syrians until thou hast consumed them:
Abarbinel thinks he had in view the blessing of Joseph by Moses, ( Deuteronomy 33:17 ) where he is compared to a bullock with horns; and these said to be the ten thousands of Ephraim, and the thousands of Manasseh; and Ahab being of the tribe of Joseph, and ruling in Ephraim and Manasseh, the prophet chose to make use of this emblem for his encouragement.