Rashi: He makes overpower. This is like "v'Avligah Me'at" (Iyov 10:20), "Mavligisi Alai Yagon" (Yirmeyah 8:18). Shod is a weak, plundered man. Hashem makes the weak overpower the strong, and plundered [cities] rule over great strong cities.

Radak: If you will say that you will trust in your fortresses, Hashem is the One who strengthens the plundering enemy over a fierce nation. So the plunderer will come against a strong fortress with Hashem's will, and conquer it. He will bring one who will capture your fortresses!

Malbim: (a) Since they reversed Mishpat to La'anah, He will reverse the order also regarding people. The Shod (weak) overpowered also the weak. (b) The plundering itself overpowered them ? they were punished for it.

Malbim: Even though the strong dwells in a fortress, it will not save him. The Shod will conquer the fortress.