A Witchers' silver sword is used for slaying monsters. If you start the game without importing a save file from the original game, Geralt must gather the components to craft such a sword to complete the quest "A Sword for Monsters" in Chapter I. The list of components is found in the document "Diagram: Witcher's silver sword".
Associated quests Edit
Geralt does start the game with this sword as part of his starting equipment, but loses it near the end of the prologue, to a dragon.