With the edge of the sword - This expression always denotes a great slaughter of the enemy.

Joshua discomfited Amalek and his people - Amalek might have been the name of the ruler of this people continued down from their ancestor, (see Clarke on Exodus 17:8 (note)), as Pharaoh was the name of all succeeding kings in Egypt. If this were the case, then Amalek and his people mean the prince and the army that fought under him. But if Amalek stand here for the Amalekites, then his people must mean the confederates he had employed on this occasion.

And Joshua discomfited Amalek and his people with the edge of the sword. Amalek being distinguished from "his people", has led some to think that Amalek was the name of the king, or general of the army, and that it was a common name to the kings of that nation, as Pharaoh was to the kings of Egypt; but for this there is no foundation in the Scriptures: as Amelek signifies the Amalekites, his people may design the confederates and auxiliaries, the other people, as Ben Gersom expresses it, they brought with them to fight against Israel. And so Jerom (z) says, by him another Canaanite dwelt, who also fought against Israel in the wilderness, of whom it is so written, and Amalek and the Canaanite dwelt in the valley, Numbers 14:25 and who were all, the one as the other, at least the greatest part of them, cut to pieces by the edge of the sword of Joshua and the Israelites, who obtained a complete victory over them; as the spiritual Israel of God will at last over all their spiritual enemies, sin, Satan, the world, and death.

(z) Ut supra. (De Locis Hebr. fol. 87. M.)

And Joshua discomfited Amalek and his people with the edge of the sword.

17:13 Though God gave the victory, yet it is said Joshua discomfited Amalek, because Joshua was a type of Christ, and of the same name, and in him it is that we are more than conquerors.

13. Joshua discomfited Amalek-Victory at length decided in favor of Israel, and the glory of the victory, by an act of national piety, was ascribed to God (compare 1Jo 5:4).

17:8-16 Israel engaged with Amalek in their own necessary defence. God makes his people able, and calls them to various services for the good of his church. Joshua fights, Moses prays, both minister to Israel. The rod was held up, as the banner to encourage the soldiers. Also to God, by way of appeal to him. Moses was tired. The strongest arm will fail with being long held out; it is God only whose hand is stretched out still. We do not find that Joshua's hands were heavy in fighting, but Moses' hands were heavy in praying; the more spiritual any service is, the more apt we are to fail and flag in it. To convince Israel that the hand of Moses, whom they had been chiding, did more for their safety than their own hands, his rod than their sword, the success rises and falls as Moses lifts up or lets down his hands. The church's cause is more or less successful, as her friends are more or less strong in faith, and fervent in prayer. Moses, the man of God, is glad of help. We should not be shy, either of asking help from others, or of giving help to others. The hands of Moses being thus stayed, were steady till the going down of the sun. It was great encouragement to the people to see Joshua before them in the field of battle, and Moses above them on the hill. Christ is both to us; our Joshua, the Captain of our salvation, who fights our battles, and our Moses, who ever lives, making intercession above, that our faith fail not. Weapons formed against God's Israel cannot prosper long, and shall be broken at last. Moses must write what had been done, what Amalek had done against Israel; write their bitter hatred; write their cruel attempts; let them never be forgotten, nor what God had done for Israel in saving them from Amalek. Write what should be done; that in process of time Amalek should be totally ruined and rooted out. Amalek's destruction was typical of the destruction of all the enemies of Christ and his kingdom.