I have read and very often imagined adapting his books to a campaign.  Haven't you found yourself trying to guess at the swords stats:

Dragonslicer a +5 Sword of Dragonslaying
Mindsword would act as a Rod of Rulership that continually functions and opeates at (at least) triple range.
Woundhealer automatically heals/restores
Shieldbreaker a +6 Vorpal Sword (that also destroys an oppenents weapon if struck in combat)

All the rest are cool too:

Coinspiner
Souldrinker
Stonecutter
Townsaver
Farslayer


Am I missing any?  I'm doing this all from memory and it has been a lot of years.

The link stats are nice adaptations, but in order to be true to form the weapons must be WAY more powerful. In the books, no power other than another Sword is able to stop or prevent the effects of a given Sword. Coinspinner, believe it or not, was the hardest, since its powers reach infinitely into time and space. Shieldbreaker was actually simple.

Shieldbreaker:
Shieldbreaker cannot be destroyed by any force other than contact with Woundhealer.
Wielder cannot be harmed by any weapon or spell (including natural weapons of non-humanoids).
Anyone striking at wielder has weapon destroyed, doing 1-20 damage to all within 15' (except wielder). The attacker must save vs. death or suffer 10-100 damage from Shieldbreaker's riposte. There is a 50% chance that any shield and/or armor used is destroyed as well. This is in addition to the wielder's normal attacks.
If the wielder attacks a foe with a weapon, there is a 50% chance the sword will behave as if the foe attacked the user as above. Otherwise it is considered a normal attack.
The sword cannot be released when foes are within 100'. It will spring into its owner's hand whenever combat of any sort threatens.
It is powerless to harm unarmed opponents. If used on an unarmed opponent, or if an unarmed opponent attacks the wielder, the wielder begins to lose STR points at the rate of 1 per round, until 3 is reached or the combat ends. Unarmed opponents may damage the wielder. Any unarmed person may make a combined STR and DEX check vs. the wielder's STR and DEX. If successful, the opponent may take Shieldbreaker out of the wielder's hand. Lost STR returns at the rate of 1 point/turn.
There is a 50% chance when attacked by more than 3 opponents in a round that Shieldbreaker does 1-4 points of damage to the wielder through exertion. This is subdual damage, only 1/4 is permanent.

Now, this may seem stupidly powerful for an RPG, as would the other swords, but keep in mind that the other 11 swords are usually held by other people, some of whom have dire intentions, and most of whom have a fear of the swords they do not possess. And some, like Townsaver and Stonecutter, are situational. If you run the campaign with the (unknown to the PC's) theme that swords that are possessed but not used will usually be lost or taken away, it balances out quite well. Throw in the gods, and it is awesome.
The best part is watching party members try to decide who will wield the weapons. I saw many a PC turn down a Sword for fear of the attention it would bring.

Deadlord36 wrote:BTW, that was quick on the link, Breach! Had you seen it before?

No, I knew there were twelve swords and I could only think of 9 . . . it started to bother me so I did a quick search and found the link.  

Well, with 12 of them, it's fairly easy to teach the players to think. I remember when they acquired Farslayer. One of the magic-users used it to kill the possessor of the Mindsword, figuring he could teleport to Farslayer's location after he used it and get the Mindsword. Took all of a minute for one of the enslaved minions to yank Farslayer out and send it right back to the mage. They didn't use it again after that.

http://www.berserker.com/FredsSwords.html

Check out the links near the bottom, specifically the Swords' Bible and the most important one: the properties of the swords.  Oh, and by the way, this is Fred Saberhagen's website.

I never got around to reading the Sword books, but I did very much enjoy the Berserker series as a teenager.