Kring is a magical black sword appearing in The Colour of Magic. It is heavily decorated with ornaments and rubies. What makes the sword so special is its ability to talk and sing. And that is also the sword's main drawback, because it just does not know when to stop (which sometimes can be a real problem). It likes to recount all the different owners it had worked with, which may or may not be an interesting conversation topic, but what it really loves to do is to complain about all the hundreds of years that it spent at the bottom of some pond or such, while it was between owners. Former owners include the Pasha of Redurant, the Archmandrite of B'Ituni, and Hrun the Barbarian. The sword also proclaims having played a prominent part in the battle of the Great Nef, where it got a slight nick in its blade.
Sentient magical swords are in every respect a double-edged weapon and can pose problems for their user. Given the degree of comatose boredom Kring's conversation (or monologues on battles, victims slain, and where it picked up that irritating little nick two-thirds of the way up my left side, look, you can just about see it if you hold me in a good light) can induce in the listener, it is no surprise that a previous owner (was he called Arthur?) threw it in a lake, where nobody was in a rush to pick it up again for another three hundred years. Indeed, had there been a Lady in that lake, she is likely to have thrown it straight back again...
(Also of the sword that Eddie Valiant tries to use in Who Framed Roger Rabbit which, instead of being any use, starts to croon Only You...)
However, instead of howling with joy at every soul taken for the dark god Arioch, this Black Sword prefers to drone on, in a tinny metallic monotone, about settling down to a nice quiet retirement on a farm somewhere, having been beaten into a ploughshare (I don't know what one of those is, but it's an existence that seems to have some point to it) (1).
If Stormbringer eventually takes the soul of its user, Kring exacts a similar dread payment in that it hijacks the ear of its user - and it doesn't let go.
It is possible that what animates Kring may be a variant on a theme of the applied magic that powers such hi-tech devices as the Dis-organiser, which Samuel Vimes, exasperatedly, throws into the sea... this may be an effect such magic eventually has on all who use it.
Even in battle, Kring keeps up an irritating running commentary, saying to Rincewind You're really not very good at this, are you?
Its current whereabouts are unknown, although it may have been dropped overboard from the back of a dragon flying at great height above a very deep sea. Whoops.
(1) The sword-beaten-into-ploughshare metaphor is culled directly from both Isaiah 2:4 and Micah 4:3 in the Bible: They shall beat their swords into ploughshares, and their spears into pruning-hooks; nation shall not lift up sword against nation, neither shall they learn war any more.