By Mark Lawson
In Hamkt's Name I Greet you.
Investigating the scrolls that were later found in the Humakt Temple at Balastor's Barracks, there was a reference to Styx River Swords, as special weapons, hardened with either a few drops of the River Styx water or in a barrel of water from the Styx. They are one of Humakt's Chosen to destroy Vampires. They were discovered origianlly by a subcult of Humakt in the First Age.
Basically any sword can be made a Styx River Sword. Procedure is a once lost art, but the procedure has been rumored to have been found recently on a HeroQuest by a nameless hero near a forgotten forge near the River Styx while questing for a flask of the magic water. 
Basically forge the new weapon, and quench in Styx River water.  It may be that you need only mix in a few droplets when forging the new blade rather than an enitre barrel full. Anyway, for all intents and purposes, the blade is a normal weapon (bronze or iron) until it is in the vicinity of a Vampire. The Blade will glow and indicate the direction the vampire is, whether invisible or not.  When used in melee with a vampire, the blade will match POW vs POW, (Humakt grants it a POW of 18 ) and if the blade wins, the hit location is automatically destroyed if armor is penetrated and cannot be regenerated.  If a Vampire is hit in the chest with a critcal hit, he is automatically destroyed by the power of the Styx Water in the blade matrix. The River water also adds +10% to hit/parry only vs. Vampires.
They are rare and extremely rare, as Vivamort followers go out of their way to destroy or hide such blades. As they cannot even touch them, they have mortal followers do the actual deeds.
They are worth at least 10,000 Lunars on an open market, and even more
to any anti-vampire cults, up to 25,000 Lunars in training and/or spells. 
1. I would say that Styx River Swords can be made using a specific Styx River Sword HeroQuest. This would be known to certain Humakti HeroQuestors.
2. The Sword is forged on the banks of the Styx and at a certain point, the Questor plunges the sword into the Styx and merges the Styx's powers with the sword.
3. I would give this a cost of 1 MP to cast. Alternatively, the sword can glow whenever it is within a certain distance (POW in metres) of a vampire.
4. In RQ3 this would be 3D6 + 6.
5. This is quite powerful, so I would give this a cost of 1 POW. When the location is destroyed, the wielder of the sword loses 1 POW.
6. These should probably be Owner Only, but there should be a ritual known to the Humakt cult that allows another person to take control of the Styx Sword, this should cost 1D3 POW to attune the Sword. Wielders of a Styx Sword should have the geas "Attack Vampires on Sight".