Achilles' heel: translation
Achilles' heel
Fig. a weak point or fault in someone or something otherwise perfect or excellent. (From the legend of Greek hero Achilles, who had only one vulnerable part of his body, his heel; as an infant his mother had held him by one heel to dip him in the River Styx to make him invulnerable.) •
He was very brave, but fear of spiders was his Achilles' heel.
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{n. phr.}, {literary} A physical or psychological weakness named after the Greek hero Achilles who was invulnerable except for a spot on his heel. * /John's Achilles' heel is his lack of talent with numbers and math./