Canto 1 - Boyhood
Bāla-kāṇḍa
Chapter 27: Viśvāmitra Teaches Rāma to Summon Divine Weapons
Text 1.27.13

वैद्याधरं महास्त्रं च नन्दनं नाम नामतः।
असिरत्नं महाबाहो ददामि नृवरात्मज॥

vaidyādharaṁ mahāstraṁ ca nandanaṁ nāma nāmataḥ
asi-ratnaṁ
mahā-bāho dadāmi nṛ-varātmaja

vaidyādharam = used by the Vidyādharas; mahā-astram ca = the great; nandanam = Nandana; nāma = named; nāmataḥ = famous; asi-ratnam = jewel among swords; mahā-bāho = O mighty-armed; dadāmi = I will give You; nṛ-vara-ātmaja = prince.

O mighty-armed prince, I will give You the famous great jewel among swords used by the Vidyādharas named Nandana.

The sword is a weapon of the Vidyādharas.