One's Achilles' heel(致命弱点)
Weak or vulnerable point; fault, esp in sb's character, which can lead to his downfall.
致命弱点;(尤指某人个性中可导致一败涂地的)缺陷。
关于Ahilles:
【希神】阿基里斯(除脚踵外,浑身刀枪不入)
When Ahilles was an infant, his mother tried to make him immortal by bathing him in a magical river.
当阿基里斯还是婴儿时,其母亲为了使他永生而在神秘河里为他洗澡。
请看例句:
Vanity is his Achilles' heel.
虚荣自负是他的致命伤。