'Weak' in the Bible

Asa cried out to the LORD his God, telling him, "LORD, there is no one except for you to help between the powerful and the weak. So help us, LORD God, because we're depending on you and have come against this vast group in your name. LORD, you are our God. Let no mere mortal man defeat you!"

Be ye strong therefore, and let not your hands be weak: for your work shall be rewarded.

Meanwhile, somebody drew his bow and struck the king of Israel at a weak spot where his armor plates joined, so he instructed his chariot driver, "Turn around and take me out of the battle, because I've been severely wounded."

Even though the invading Syrian army was relatively weak, the Lord handed over to them Judah's very large army, for the people of Judah had abandoned the Lord God of their ancestors. The Syrians gave Joash what he deserved.