A sword was a typical weapon of war. The Lord is saying that the house of Jeroboam is going to be destroyed. This does not necessarily mean that Jeroboam himself will fall by the sword; the house of Jeroboam refers to his family, his dynasty. The Jehu dynasty, of which Jeroboam was the final substantial member, ended in 753 BC with the assassination of Zechariah, Jeroboam’s son (2 Kings 15:8–12).
9 the high places of Isaac shall be made desolate, and the sanctuaries of Israel shall be laid waste, and I will rise against the house of Jeroboam with the sword.”