"In that day Egypt will be like women, and will be afraid and fear because of the waving of the hand of the LORD of hosts, which He waves over it." - Isaiah 19:16
This "fear" is not necessarily a sign of weakness but of wisdom. While he may be speaking of a fear which non-warriors have when they are attacked and have no means at all of protecting themselves, something else may be going on here. For consider what this "fear" brings about:
"In that day five cities in the land of Egypt will speak the language of Canaan and swear by the LORD of hosts;..." - Isaiah 19:18
That fear of Judah and Judah's God drives them to Judah's God. The fear of a woman, Rahab, drove her family to the God of Israel (Joshua 2:8-11). This was an efficacious fear, a wise fear, a fear we should wish upon all unbelievers of the true God and His ways.
This is a fear which is the delight of the LORD - "His delight is in the fear of the LORD" Isaiah 11:3
Because this is a fear that leads to salvation.