Magic Swords

The sword Tyrfing connects Poul Anderson's The Broken Sword (New York, 1973) back to an Eddaic poem and a saga but also forwards to Anderson's Hrolf Kraki's Saga which lists four "...magical swords...":

Sighurd's Gram;
"...Tyrfing the accursed...";
Skofnung, given to Hrolf by an elven woman;
Lovi, of which more will be told later in the Saga (p. 129).

Magic swords never rust and always bite although Excalibur is not listed here.

Poul and Karen Anderson wrote a King of Ys tetralogy;
The Broken Sword refers to Ys;
The Demon Of Scattery refers to The Broken Sword;
War Of The Gods, like The Broken Sword, features Odin;
Hrolf Kraki's Saga, like War Of The Gods, describes Odin's descendants;
Hrolf Kraki's Saga refers to the broken sword.

Thus, here are eight connected volumes: four by Anderson; four by the Andersons.