Sting (Middle-earth)
Sting has the magical ability to detect orcs or goblins nearby, glowing blue in their presence, as it did when the Fellowship encountered orcs in the mines of Moria. Tolkien establishes this as a common property of First Age Elf blades, particularly those forged in Gondolin. Sting is also exceptionally sharp. Bilbo manages to thrust it without effort deep into a wooden beam at Rivendell. Frodo also wounds a troll in Moria, after Boromir notches his own sword with his attempt. Sam uses Sting to cut through the giant spider Shelob's strong webs with ease, and also wound the spider, driving it away from the paralyzed Frodo.
Middle-earth weapons and armour
Sting is a knife in "The Hobbit" and "The Lord of the Rings". Although made by the Elves as a large knife, it functioned well as a sword for the smaller race of Hobbits. Bilbo Baggins named the weapon after using it to fend off the giant spiders in Mirkwood forest, then later passed it on to Frodo to use in his quest to destroy the One Ring. Sting would glow blue whenever orcs or goblins were nearby.