“Therefore thus says the Lord Yahweh, Behold I am against Pharaoh, king of Egypt, and will break his arms, both the strong and that which was broken, and I will cause the sword to fall out of his hand. And I will scatter the Egyptians among the nations, and will disperse them through the countries.”
Not only had Pharaoh been defeated and turned back, but God also intended to make him powerless, like a man with two broken bound up arms who tries to wield his sword and finds that it falls out of his hand. When Nebuchadnezzar attacked Pharaoh would be utterly defeated, and the fighting and the defeat would be such that many Egyptians would desert Egypt and be scattered among their neighbours. This was deliberately described like this so as to suggest a parallel to what had happened to Israel and Judah. Egypt will be no better off than they.
In fact by the time Nebuchadnezzar attacked Egypt after the siege of Tyre there was a new Pharaoh. Hophra had been killed in civil war after a disastrous campaign in Libya had caused an internal revolt, and was replaced by the leader of the revolt, Ahmose II. The broken arm was replaced by another broken arm. The civil war left Egypt in no position to defend itself against a powerful enemy. The result would be that many would flee the country for one reason or another.
Statues or images of the Pharaoh often had an arm flexed, wielding a sword in battle, and Pharaoh Hophra was reputed to have taken a second formal title that meant 'possessed of a muscular arm' or 'strong-armed', which may be in mind here.