Asi Khanda

The Asi Khanda was the first double-edged, straight bladed, blunt tipped sword created in ancient times. Unlike the swords made in its image, the khandas, the Asi Khanda has a back spine on the blade to add more strength. It was also made so the blade is wider and flatter, making it a formidable cutting weapon. It also had a good advantage to infantry over light cavalry enemy armies.
The blade was said to originally be for the Goddess Durga in her in the crusade to slay demonic beings during the what is estimated to be the early stages of the Ghulat Wars. In particular the Asi Khanda was crafted for Durga as she was the only deva at the time who could confront Mashishasura, a wrathful deity known as an Asura.
Brahma, the Creator of Satyaloka had given Mahishasura the power not to be defeated by a male or any deity in exchange for years of observing penance. Mahishasura, thus using his powers, unleashed a reign of terror on the various other loka of the mortal and the divine. He created cosmic disruption and defeated the gods of Sun, Fire, Earth, Thunder and all other nature gods. All the Devas pleaded Brahma to do something about this after a series of defeats.
Shiva, made a request to all the devas at the time to combine their divine energies together. Thus, to save the 3 worlds, Vishnu, Shiva, Brahma and all of the other Deva (Indra, Varuna, Surya, Agni, Yama, Vishwakarma etc.) emitted beams of fierce divine energy towards Parvati as a vessel. The process covered her in a blinding sea of light spread in all directions of the universe like a supernova and altered her into a new form called Durga. The light reached the pious priest Katyayan, who recovered metal ore that absorbed some of that divine energy and had it fashioned into the Asi Khanda. With this new blade Durga lead a new fight against Durga proceeded to gather an army to fight against Mahishasura and his evil minions, who had began a reign of terror on both heaven and earth. After nine days of fighting Durga finally reached Mahishasura and by the tenth day the asura had been slain by the goddess and peace was restored to the world.
Thus blades called Khandas were made in its image.