The predicted brutal ruler would probably be a foreigner who would be cruel to Egypt. Isaiah uses expressive words to suggest that there would be no escape from his rule.
It is difficult to determine which specific ruler this part of the prophecy points to. There are many different opinions. Some suggest that the fierce king would be the little horn
mentioned in Daniel 7:1–28. Others point to Psammetichus, Piankhi of Ethiopia, Sargon II of Assyria, Ochus (also known as Artaxerxes III) or Esarhaddon, who conquered Egypt in 671 BC. However, understanding a general picture of the political landscape waiting for Egypt is more important.
4 and I will give over the Egyptians into the hand of a hard master, and a fierce king will rule over them, declares the Lord GOD of hosts.