The unnamed 18th Centruy Sagitta Silver Saint was sent to Italy along with Cerberus Saint, Auriga Saint, Canis Major Saint and Musca Saint to investigate Specter activities near a cathedral in a forest, where they were killed by Specters. (Although in the anime he was able to kill one Specter with his Phantom Arrows)
Sagitta, along with Cerberus and Auriga, was resurrected by Hades, and sent back to the Sanctuary to kill Athena. They were ultimately finished by Aries Shion and Libra Dohko. Before they died, their souls returned to good and asked Athena for forgiveness.