Karna sacrifices his armour and gains Indra's weapon
Karna, famed for his generosity, worships the sun god daily. Indra, lord of the gods, comes disguised as a Brahmin and asks for the one thing Karna cannot afford to give: his innate, invulnerable armour and earrings. Karna gives them anyway.
Vasushena, who would become known as Karna, grew into a man of formidable power and a single, unwavering principle: generosity. The valorous one worshipped his father, the sun god, with such devotion that he stood in meditation until his back was burnt. During that time, there was nothing the brave, truthful, and great-souled man would not give to a Brahmin who asked.
Indra, the king of the gods who looks after the welfare of all creatures, knew of Karna’s vow. He also knew that Karna, born with the sun’s protection, was invulnerable. To aid his own son Arjuna in a future conflict, Indra devised a plan. He came to Karna in the form of a Brahmin begging for alms.
The Brahmin did not ask for gold or cows. He asked for the radiant natural armour and earrings — the kavach and kundala Karna was born with, the source of his invincibility.
Karna did not hesitate. He did not bargain or plead. Without a thought, and with blood streaming from the wound, he cut off the natural armour and the earrings from his own body and offered them to the Brahmin with joined hands.
The amazed Shakra — Indra — revealed himself. He gave Karna a shakti, a divine spear, and said, "Whoever you wish to kill among the gods, the asuras, humans, gandharvas, serpents, and rakshasas with this weapon, will certainly be killed."
Earlier, he had been known as Vasushena. But after this deed of cutting his own armour away, he became known by the name Vaikartana Karna.