Shiva Dhanush
Pinaka or Shiva Dhanush is the bow of the Hindu god Shiva. It was given by Shiva to his devotee King Devaraatha, the ancestor of King Janaka. It is mentioned in the Hindu epic Ramayana, when its hero Rama (another avatar of Vishnu) breaks it to win Janaka's daughter as his wife.
Vishwakarma crafted two divine bows. He gave Sharanga to Lord Vishnu and Pinaka to Lord Shiva . King Janaka of Mithila had a daughter named Sita. In earlier part of her life, Sita while playing with her sisters had unknowingly lifted the table over which the bow had been placed; which was something no one in the kingdom could do. This incident was however observed by Janaka and he decided to make this incident as the backdrop for swayamvara.
Later, Janaka had announced that whosoever wanted to marry Sita had to lift the divine bow and string it. The bow was broken by Ayodhya's prince Rama when he attempted to string the bow, during the swayamvara of Sita, thereby winning the princess's hand in marriage. After the marriage when his father Dasharatha was returning to Ayodhya with Rama, Parashurama obstructed their path and challenged Rama for breaking his guru Shiva's bow. Rama extolled the sage. After that Dasharatha prayed to the sage to forgive him but Parashurama remained enraged and brought out Vishnu's bow. He then asked Rama to string the bow and fight a duel with him. Rama snatches the bow of Vishnu, strings it, places an arrow and points it straight at the challenger's heart. Rama then asks Parashurama what he will give as a target to the arrow. At this point, Parashurama feels himself devoid of his mystical energy. He realizes that Rama is the avatar of Vishnu, his successor and his superior. He accepts Rama's superiority.
*(( Another tale of Pinaka revolves around the tale of Lord Vishnu fighting Lord Shiva,mentioned in Seventy fifthe sarga of Bala kanda of Ramayana.Pa'rashuram narrates this to Lord Rama before challenging him to string Sharanga.The story goes like this-The Devas wanted to test the superiority of Lord Vishnu and Lord Shiva and asked Lord Brahma to create a difference of opinion between them.In the battle that ensued,Lord Vishnu utters a battle cry "hum" which paralyzes the Devas and Lord Shiva.His bow is rendered useless, and Lord Vishnu's bow Sharanga prevails.[1][2][3] This Pinaka was broken later by Lord Rama,who also snatches Sharanga from Parashurama and gives it to Varuna,lord of the oceans,for safekeeping.))*
Although reference is still to be inserted from Puranas (ancient Hindu texts) there is some connection of Pinaka with the life of Maharshi Dadhichi a sage who helped devas to defeat the asura Vritra and later on request gave up life and provided his bones for making a Vajra which Indra used to kill the Demon Vritrasura.