Sting

Sting is among the weakest of artifacts. If you touch it, even if you are of the wrong alignment, then it will not blast you unless you somehow are an orc. For all purposes, Sting is only a normal elven dagger, except that it happens to do more damage to orcs.

Also, if you wield Sting, you can detect the location of any orc on the level, and you will notice when NetHack sends in large teams of orcs.

Name it to make it
Unlike most artifacts, you can create Sting by chaning the name of any random elven dagger to "Sting". This can only fail if Sting already exists. An elf Ranger can always start the game with Sting, if he or she wants to. So can anyone who finds a wooden dagger dropped from a hobbit.

Many players do not bother to do this. Sting is only useful against orcs, many players can already kill orcs, and the existence of Sting decreases the probability of the dungeon randomly containing another artifact (that hopefully is not Sting).

If you do not create Sting, you still have the chance that when offering corpses, your god will give you Sting. Then hope that your second gift is Frostbrand.

From Tolkien
"Sting" is actually the name of a dagger from J.R.R. Tolkien's novel The Hobbit and novel trilogy The Lord of the Rings. Sting was the usual weapon of the hobbit called Frodo. It was most famously wielded by the hobbit Sam in his fight against the giant spider Shelob.

Sting glowed blue to detect the approaching of orcs. Thus, Sting in NetHack is a weapon for use against orcs.

From Dudley's dungeon
In the Dudley's dungeon strip of 18 June 2004, Sting would glow blue if you gave it batteries, except that batteries will not exist until someone invents them after the time of NetHack.