This would solely be based on displayed feats, not useless hollow statements.
1: Supreme Brahmastra - Indrajit used it against Rama's army knocking out everyone except Hanuman and Vibhishan. Almost 67 crores vanaras were killed and rest were incapacitated/mortally injured. No celestial weapon in Ramayana or Mahabharata comes close to its feat.
2: Supreme Agneyastra(Empowered by Rishi Agnivesha) - Ashwathama used it on 15th day of the war after Narayanastra was baffled. It reduced an akshouhini of Pandava army was was seemingly baffled by Arjuna's Brahmastra. But in reality, Vyasa revealed that boon of Shiva to Krishna saved them from that weapon. Indicating Krishna himself rendered it futile. Else it would've burnt whole army.
3: Brahmashira - One of the weapons which relies more on statement than real feats. It was said to destroy the universe if fired on a weaker enemy, but Nothing happened when Ashwathama used it against Parikshith. Still, it's far superior to other weapons used in Kuru war, as when it was about to collide with the weapon of same kind fired by Arjuna, Vyasa and Narada intervened to prevent massive collateral damage. Arjuna never used this weapon before this particular instance.
4: Pashupatastra - Yet another statement hyped weapon. But still far more powerful than others. Arjuna used it against Kalakeyas and Poulomas after his other heavenly weapons were futile against them. Arjuna used this weapon instead of the Brahmashira, suggesting that the Brahmashira was intended for even more dire situation, hence ranked below it.
5: Narayanastra - Most powerful weapon of Vishnu, which cannot be countered by regular means. It would gradually increase its power as Opponent resists it more. Ashwathama used it to kill a huge chunk of pandava army, and it could only be baffled by submission and nothing else as decreed by Vishnu himself.
6: Vaishnavastra - Yet another powerful weapon of Vishnu. Bhagadatta posessed a unique version of the same which would've killed Arjuna had Krishna not intervened. Krishna used it to baffle Varunastra used by Varuna in a battle.
7: Tamasa - A unique weapon built by Brahma which is supposedly presided by Rahu. Ravana used it against army of vanaras to scatter them in Multiple directions. Vanaras, crores in number.
8: Higher Brahmastra - Used by Drona, Karna and Arjuna in the great war. Karna used it to defeat the Aindrastra of Arjuna. Drona and Karna's weapons did severe damage to Arjuna’s chariot and was saved by Krishna and Hanuman from Blasting.
9: Vajra - Most powerful weapon of Indra. Indra used it to slay the invincible demon Vritra. Arjuna used it against Nivatakavachas to extinguish them from existence. He also utilised it to slay Jayadratha and against Karna on 17th day.
10: Higher Aindrastra - Arjuna's Aindrastra was near invincible. Bhishma, Drona and Ashwathama failed to counter it. And he used it to slay formidable soldiers multiple times. Only karna managed to baffle it and even he too fled from it once.
