Achilles' heel

Achilles was the son of Peleus and a nymph Thetis. Soon after he was born his mother tried to make him invulnerable to weapons by dipping him in river Styx that seperated the labd of living from the land of dead. Every part of his body that touched the waters became invulnerable to any kind of weapon expect for his heels because his mother had held him by his heels. During the Trojan war, Paris who had learnt the secret of his vulnerable heel secretly striked him with a poisonous arrow when he was in a meeting with Priam and killed him with treachery.