プログレッシブ和英中辞典(第4版)の解説
いわせる【言わせる】
あっと言わせる
astonish／amaze／take a person's breath away
彼らにあっと言わせてやるぞ
I'll make them sit up and take notice.／I'll give them 「a surprise [something to think about].／《米口》 I'll bowl them over.
僕に言わせると，あいつは能なしだ
「In my opinion [If you ask me], he is incompetent.
彼にも言わせてやれ
Let him have 「a chance to speak [his say], too.