Astra (astra)

An astra is a celestial weapon, an ordinary missile charged by mantra with the power of a presiding deity, as distinct from a shastra which is a weapon wielded by hand. Astras must be learned from a teacher or won by austerity, invoked by the correct formula, and withdrawn by another, and a warrior who forgets the recall formula is helpless. The Mahabharata treats them as instruments of mass destruction whose use is governed by an etiquette that collapses under pressure, most disastrously when Ashvatthama and Arjuna aim the Brahmashira at each other.