The divine weapons that were used by Bhagvan Sri Ram in the Ramayana were presented by Sage Agastya to Him. Sri Ram met Sage Agastya in the Dandaka forest and the meeting is mentioned in the Aranya Kanda of the Ramayana.
Agastya gifted Sri Ram Vishnu’s Bow – the divine bow inlaid with gold and encrusted with gems was designed by Vishvakarma. The bow was also known as Brahmadatta as it was once given to Vishnu by Brahma.
Two quivers which are inexhaustible was the next divine gift. They were given to Sage Agastya by Indra. The arrows in the quivers will never run out in a war.
Sage Agastya then gifted Sri Ram a divine sword with a silver scabbard. Vishnu used to fight asuras using this sword.
An armor that cannot be pierced by weapon was also given to Sri Ram. This was gifted to Sage Agastya by Indra.
Sage Agastya also said that when Sri Ram needs a chariot, Matali, the charioteer of Indra, will bring the chariot of Indra and He will be able to use it.
All the above said weapons were used by Bhagavan Sri Ram in the battle against Ravana and his forces.