not brave or determined enough to defend your beliefs against others

Instead of defending traditional values, the church frequently seems weak-kneed and irresolute. 教会不但没有去维护传统的价值观，反而常常表现得软弱且犹豫不决。

made to feel weak and likely to fall by emotion

She stood dazed and weak-kneed beside the coffin. 她站在棺材旁边，头晕目眩，膝盖发软。