Bilbo Baggins’s sword in Peter Jackson’s The Hobbit: An Unexpected Journey is called Sting.
Bilbo finds the blade in a troll hoard alongside the swords Glamdring and Orcrist. Elrond later identifies the weapons as blades made in the ancient Elvish city of Gondolin. Although small by the standards of the weapons carried by warriors, Sting becomes an important part of Bilbo’s adventure.
The sword glows blue when Orcs or Goblins are nearby. This property helps Bilbo and his companions detect danger in dark passages, including the caves beneath the Misty Mountains.
Bilbo eventually uses Sting against giant spiders in Mirkwood. He names the sword after escaping those creatures, and the weapon later becomes associated with Frodo Baggins as well. It is distinct from Andúril, Aragorn’s reforged sword, which belongs to The Lord of the Rings storyline.