Vijaya (bow)

Vijaya or Vijaya Dhanush ('Victory' in Sanskrit) was the divine bow of Karna. This bow is said to give sure victory to the possessor. Parasurama gave Vijaya to his student Karna, who already had terrific skill, making him virtually invincible. Lord Krishna devised a plan to kill Karna and asked Arjuna to kill Karna when he was weaponless trying to lift his sunken chariot wheel, even though it was highly prohibited or against the rules of engagements in war, to kill an unarmed warrior.

Creation
The bow Vijaya was specially made by Vishvakarman for Lord Shiva to destroy the city of Tripura built by sons of Tarakasura. Lord Shiva destroyed Tripura by firing Pashupatastra from Vijaya. Later, Lord Siva gave this bow for safekeeping to Lord Indra, who frequently wielded the bow in his fights with the Asuras. The Asuras feared the bow due to its destructive abilities.

Parshurama receives Vijaya from Indra
Lord Shiva instructed Indra to give the bow to Parasurama for the task of combating the evil prevailing in the kshatriyas of the world. On 21 different occasions, when the ruling Kshatriyas (the martial caste) began oppressing their subjects and committing sin, Parasurama - armed with the Vijaya bow - hunted them to the brink of extinction, nearly ridding the world of the kshatriyas. Each time, Parasurama donated the territory won from the kshatriyas to brahmins (the academic/teaching caste) for re-establishment of order.

Karna and Vijaya bow
Parasurama takes Karna as his student, as told in the Mahabharatha. Since Karna was a diligent and worthy student, Parasurama blessed Karna with the Vijaya along with other celestial weapons. Karna used the Vijaya bow only once in his life, during the Kurukshetra war, on the 17th day, when he fought against Arjuna (who was using the Gandiva). Karna was known by the name 'Vijaydhari' meaning 'wielder of the Vijaya bow'.

Knowing Karna's might, Krishna on the 17th day warned Arjuna, called Karna as the foremost among the warriors and not to underestimate Karna:

"Hear in brief, O son of Pandu! I regard the mighty car-warrior Karna as thy equal, or perhaps, thy superior! In energy he is equal to Agni. As regards speed, he is equal to the impetuosity of the wind. In wrath, he resembles the Destroyer (Shiva) himself. Endued with might, he resembles a lion in the formation of his body. He is eight ratnis in stature. His arms are large. His chest is broad. He is invincible. He is sensitive (about his manhood and honour). He is a hero. He is, again, the foremost of heroes. He is exceedingly handsome. Possessed of every accomplishment of a warrior, he is a dispeller of the fears of his friends. No one, not even the gods with Vasava (Indra) at their head, can slay the son of Radha, save thee, as I think. No one possessed of flesh and blood, not even the gods fighting with great care, nor all the warriors of the three worlds fighting together can vanquish that car-warrior."

- Lord Krishna to Arjun

With this bow Karna overpowered Arjuna on the 17th day of the Kurukshetra war. Realizing that Karna with the Vijaya bow is invincible, on the 17th day Krishna advised Arjuna to kill unarmed Karna against the rules of engagement of the war, who had relinquished his bow and was busy trying to lift his sunken chariot wheel.

Features of Vijaya bow
The string of this bow cannot be broken by any kind of astra or any divine weapon. Every time an arrow is released from this bow,it created a terrible twang, which is said to be loud as thunder, causing terrible fear on enemies and produces flashes of light, brilliant as lightning, which blinds the enemy. Every time an arrow is aimed, the energy of the arrow is amplified by multiple times as this bow is charged with sacred mantras. No weapon, not even the mighty Pashupatastra, can harm a warrior who has Vijaya Dhanush in his hand.