achilles' weak point was his heel, because he was held by the heel and dipped into a magical river which gave him immortality and invincibility wherever the water touched him . he died by an arrow to his heel

duryodhana's weak point was his loins , because he wore a loin-cloth when he went to see the Gandhari, who looked at him with eyes which had been blindfolded for all her married life, out of duty and devotion, and made whichever part she saw, immortal and invincible. he died when bhima hit him below the waist , in the mace fight,