Caption: "Through a mirror, darkly..."
Caption: The Scimitar
Caption: Shinzon's massive warship, on the main viewer
Caption: Nemeses collide
Caption: Face off
Along with a massive weapons array, the ship can "transform" itself into a thalaron weapon, a weapon that uses thalaron radiation to wipe out life on the genetic level. Shinzon planned to take the Scimitar to Sector 001 and use the weapon to wipe out Earth, until Picard and the Enterprise-E intervened.
Before the vessel was destroyed, it managed to survive both a head-on collision with Enterprise and the subsequent sheering away from the starship.