Achilles was a soldier . When he was a baby , he was put in a sacred stream . This water made him safe against all weapons , he could not be wounded . But the nurse held Achilles by his heel , so the sacred water did not touch his heel . That is why , Achilles could be wounded in the heel . It was his weak spot . Hence , this phrase , the heel of Achilles means a person's weak spot or the weak part in someone's character .
Examples .
The desire for publicity became her Achilles heel .
The enemy had an Achilles heel somewhere , if only he could find it .
I think Frank vanity is his Achilles heel .
I am trying to lose weight , but ice cream is my Achilles heel .

Some common emotional Achilles heels are :
Fear of the unknown
Feeling trapped
Being ignored
Feeling left out

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