The Black Sword
From Slinkiwiki
"'Black Sword,' I crooned, 'kill this fat bugger for me.' 'Alas Master, this one is too strong for me. His destiny lies elsewhere.' 'Black Sword,' I said, 'make fire. Let us roast the fatted calf.'"
- Oscar Wilde on the Black Sword
Slink has the holy, righteous, good-doing blade, the MSOP, which not only guides him to righteous victory, but amplifies his ability to use holy magic in his battle against the forces of evil.
Krine gets an evil sword that thirsts for blood and flies up to smack him in the head if he gets more than a couple feet away from it.
Yeah, I think we both know who got the better deal on this one.
This is about the Myriad Lands weapon-slash-plot device.
Origins?
The exact origins of the sword are unknown to everyone except the writer. All that has been revealed so far is that Krine's evil-ish brother, Kurinen, delivered it anonymously to Krine specifically to annoy him. Yeah, he's like that. Whether or not Kurinen is responsible for the sword's construction or curse is not yet revealed either.
Powers?
The Black Sword is cursed, as previously mentioned. When it finds someone who wields it, it does not let the wielder leave it too far from their person. More than a few feet, and it literally flies through whatever obstacles are between the sword and the unlucky victim with no small amount of force, quickly either knocking them senseless or convincing them not to leave the sword too far from them.
On top of that, the curse is also such that the sword seems to desire to kill; upon being stuck with the sword, the unfortunate victim starts having nightmares of increasing twisted intensity. They tend to be dreams portraying the victim killing or seeing the horrific deaths of people they care about or see often, eventually leading up to layers of "waking nightmares," the sort that leave the person unable to tell if they've actually woken up or are just in a new terror. If the victim kills another person with the sword, the nightmares temporarily abate. Very temporarily.
On the up side, the sword is strong and deadly sharp; aside from being able to punch through armor, it cuts through exposed flesh seemingly at a touch. Other than that, it doesn't seem to have anything positive about it.