The origin of Vaishnavastra comes from Valmiki Ramayana. Narayana became the embodiment of arrow and slayed Madhu and kaitabha with it.
- O Kakutstha! When he was lying down on the great ocean and could not be seen by the gods and the asuras, the god Narayana created this arrow. While he was invisible to all creatures and was filled with rage in a desire to kill the evil-souled Madhu and Kaitabha, the brave one fashioned this excellent arrow. Desiring to create the three worlds, he used this excellent arrow to kill those two in the battle and created the worlds.
Valmiki Ramayana Chapter 7(55) Critical Edition
- This arrow is full of energy and you are scared because of that. Earlier, this belonged to the eternal god who is the creator of the worlds. The great-souled one created this great arrow to slay the two daityas, Madhu and Kaitabha. Only Vishnu knows about this arrow, which is filled with energy. Earlier, it was the embodied form of the great-souled Vishnu himself
Chapter 7(61)
It contains the essence of Vishnu .
Rama bestowed it to Shatrughan who invoked it against Lavanasura and avenged the death of Mandhata
- The best among archers stretched his bow all the way back up to his ears and shot that large arrow towards Lavana’s broad chest. Swiftly penetrating his chest, it entered rasatala. Having gone to rasatala, the celestial arrow was worshipped by the gods. It then quickly returned to the descendant of the Ikshvaku lineage
Vaishnavastra was given as a boon by Vishnu Mahābhārata 7.28–29
- सा वव्रे विष्णुसदृशं पुत्रमस्त्रं च वैष्णवम् ।
- बभूव च सुतस्तस्या नरको नाम विश्रुतः ।
- अस्त्रं च वैष्णवं तस्मै ददौ नारायणः स्वयम् ॥
- “She requested a son equal to Viṣṇu and the Vaiṣṇava weapon. Her famous son Naraka was born, and Nārāyaṇa himself gave him the Vaiṣṇava weapon.”
There is no counter to it . Arjuna despite possessing Pashupata and other weapons couldn't counter it as per Krishna
- नास्यावध्योऽस्ति लोकेऽस्मिन्मदन्यः कश्चिदर्जुन । तस्मान्मया कृतं ह्येतन्मा भूत्ते बुद्धिरन्यथा ॥
- "In this world, Arjuna, there is no one except me who cannot be killed by it. I did this for that reason; let your mind not think otherwise."
- अवोचं चैतदस्त्रं वै ह्यमोघं भवतु क्षमे । नरकस्याभिरक्षार्थं नैनं कश्चिद्वधिष्यति ॥
- Guarded by this weapon, your son will be a crusher of enemy hosts, impossible to overcome in all the worlds at all times."
- तस्मात्प्राग्ज्योतिषं प्राप्तं तदस्त्रं पार्थ मामकम् । नास्यावध्योऽस्ति लोकेषु सेन्द्ररुद्रेषु मारिष ॥
- "For your sake I have made it otherwise: deprived of that supreme weapon, kill the great asura, Partha."
- अवध्योऽयं महास्त्रेण भगदत्तः सुरासुरैः । वैरिणं जहि दुर्धर्षं भगदत्तं सुरद्विषम् । यथाऽहं जघ्निवान्पूर्वं हितार्थं नरकं तथा ॥
- Protected by that great weapon, this Bhagadatta cannot be killed by gods and asuras. Kill the unassailable enemy Bhagadatta, foe of the gods, as I once killed Naraka for the good of the world."
There is no counter to it because it's blessed with boons from Narayana