You can't take advantage of others，weakness. You know that's his Achilles'heel.

你不能利用别人的弱点。你知道那是他的致命弱点。

I don't have other choices.

我别无选择啊。

重点讲解:

That's his weakness.

That's his Achilles'heel!

Achillcs' heel来源于荷马史诗。Achilles(阿喀琉斯)在特洛伊战争中身经百战，屡建奇功，但是唯有脚后跟是其致命弱点。后来阿喀琉斯被仇敌射中脚后跟而身亡，最后死于自身的致命弱点，所以后来人用Achilles'heel来代指致命的弱点，不仅比weakness语气更强，而且更加形象。