Seven Swords

The Seven Swords were swords that were originally possessed by the Seven Lost Lords that Caspian and the crew of the Dawn Treader voyaged to find in The Voyage of the Dawn Treader. Each sword possessed magical properties and when all were placed on Aslan's Table at Ramandu's Island, the darkness emanating from Dark Island that was slowly overtaking the lands of Narnia would be lifted. It is never explained in the film why Aslan entrusted the protection of Narnia to Telmarine Lords. Peter Pevensie's sword, Rhindon, was also shown to have similar magical properties, though it was not one of the seven; that could be as the seven swords are old narnians

History
The seven lords would hold on to their swords during the journey beyond the Lone Islands.

Lord Bern would be a prisoner at the Lone Islands who gave his sword to Caspian and his crew when the islands was purged of its slave traders.

Lord Restimar was turned into gold at the Deathwater Island but his sword remained its state as a metallic sword rather than golden. The sword was retrieved by Caspian, Edmund, and Lucy.

Lord Octesian, who was at the same island, died of an unknown cause with his clothing and skeletal corpse remaining at a river of gold riches.

Lords Argoz, Mavramorn, and Revilian would be put into an enchanted sleep until the darkness was gone. When there were first found by Caspian and his crew, they found the frozen lords near a buffet table with their swords under the weeds.

Lord Rhoop was a surviving lord that spent some time on the Dark Island. Later on, he would be found by Caspian along with his sword.

The swords would eventually join once Eustace places the last sword (Rhoop's sword) along with the other six, ridding Narnia of its darkness.