noun
Achilles' heel - a weakness or vulnerable point in someone or something
-
The lack of proper cybersecurity measures is often considered the company's Achilles' heel.
-
His Achilles' heel is definitely his love for junk food.
-
She knows that her fear of public speaking is her Achilles' heel.
-
Procrastination is my Achilles' heel when it comes to meeting deadlines.