The Shay-Keded, or “Sand-Slaughter”, was created by a fanatical death cult (a sub-sect of the Mortuary Cult of Nehekhara) called “The Warriors of Endless Time” millennia ago. The purpose of the blade was very simple, however. It was created to destroy.
The Shay-Keded is on inspection a crudely beaten bronze kopesh (an ancient form of sword, similar to a backwards sickle) with embossed hieroglyphics down its length. Despite its dilapidated appearance, it has a wickedly sharp edge that shows no signs of it even having been sharpened.
The blade lacks a crossbar, but around the hilt is woven was appears at first to be dull leather, but on closer inspection is flayed human skin. Worse still, when holding the blade by the hilt, one can feel a dull pulse coming from the flesh bound around the base.
For those who can read the ancient Nehekharan text, it tells of its purpose and its perceived destiny:
“Shay-Keded was born in fury and ambition and shall die in the heart of its truest master.”
(One could adapt the blade to hail from any ancient civilisation, however, one influenced by Egyptian culture is most fitting.)
The Shay-Keded has a magical vampiric ability in that it feeds off of the life-force of its victims, fuelling the magical energy of its wielder.
In mechanical terms, should the blade deal at least 1 Wound to an opponent, then the wielder gains +1 to their Mag Characteristic during their next round of combat. Should they not cast a spell during this following round, the bonus Casting Dice becomes a Chaos Dice that remains (and is stackable with other Chaos Dice produced through other means and as a by-product of this ability) until the next sunrise.
In terms of fluff, any wound caused by the Shay-Keded seems to bleed sand for a few moments before acting as a normal wound (that is, by releasing blood). Any limb or body part cut off with this blade shatters into sand when it hits a hard surface. This is also the case for items held by the victim (although magical items are unaffected). Items of Best Quality are not destroyed on a roll of 6+ on a d10, and are merely reduced to Poor Quality. These items appear to have weathered many hundreds of years in an instant.
(One could adapt the abilities to give a bonus to casting rolls in the following turn, but then count as a casting penalty if not used immediately.)
Crafted by the Warriors of Endless Time, the blade was eventually taken up by one of Vashanesh’s lieutenants, a vampire of considerable skill himself. When, however, Nagash the First Necromancer fell after his vampire servants rebelled, the blade was whisked away north, to await the return of Vashanesh.
However, those who bore it away eventually doubted the return of their lord, and held close to the blade, keeping it as an heirloom for the master of their house, which they named House Vasilikov in the local Kislevite fashion of the North.
The Vasilikov family eventually settled in the doomed city of Praag, and have since ruled over their little slice of the underworld of that wretched city with an iron fist and the bronze Shay-Keded.
(One could adapt the history to be that after a great calamity the blade was secreted away to be returned to its old master. However, the custodians of the blade became jealous and refused to return it once their master returned, and have since held it.)