Explanation:
At the time it was customary for prominent personalities to have personal paraphernalia that was often named. The conch shell were unique to each warrior and could be often recognized just by the sound. In the battle of Virata where Arjuna was disguised, he was immediately recognized by the Kurus when he blew his conch shell.

It is also interesting to note that only those warriors whose concshells have been named in the last three verses survived (with the exception of Satyaki who is called unconquerable). All the other warriors, from Bhisma to Abhimanyu were slain in the battle.

Srila Prabhupada comments, "Sanjaya informed King Dhritarashtra very tactfully that his unwise policy of deceiving the sons of Pandu and endeavoring to enthrone his own sons on the seat of the kingdom was not very laudable. The signs already clearly indicated that the whole Kuru dynasty would be killed in that great battle."

Please read the Sanskrit Verse and the Prabhupada's Purport.