Caladrex or Caladrexian steel was used to forge weapons of superior edge and durability by the blacksmiths of that ancient and now lost city. An entrance to that now buried city was discovered by Garvey Dire and Ntashia Dire through a cavern in the cliffside of the Rift, and there is another known entrance through the Valley of Diamonds.
This lost city beneath the Martian planetary crust was at the time partially controlled by a malicious computer entity known as Sved who could also appear in apparitional or semi-substantial form. Another portion of Caladrex is controlled by Thenylis, High Priestess of the Omnipotent Vackri, who rules over the remnants of the once great people.
Caladrex steel may or may not have been actual steel at all, but in reality an alloy unknown to exile, Galbran, or Muvari, and even to the mad wizard Sar Savaht.