Storm of Ascendance
Isilian steel was created by Tam Isilia, now the royal armorer of City B, almost seventy years ago. He taught the techniques to his apprentices (some of which were his sons), and one or more of them took their teachings to City A. No one outside of Isilia’s apprentices has been able to reproduce the technique. It is reputedly extremely difficult and time-consuming to craft, and thus weapons (and, more-so, armor, for more material is required) forged of this steel are near priceless and rare indeed. The elite royal guardsmen of both kingdoms are equipped with them, and heroes of impressive renown from City A are gifted with a weapon on occasion, as the king (and the Book of Champions) dictates. Otherwise, exorbitantly wealthy nobles have sometimes commissioned a few. They have also been known to turn up in the oddest of places in the hands of the strangest people and (sometimes) creatures, with no record of their creation.
Isilian steel is unnaturally durable, and holds an edge better than any mundane alloy. The magical composition gives it incredible resilience, and that same magical structure allows mages to channel their power through the Isilian weapon. Using the weapons as a catalyst in this regard can generate unique effects for the output spells.
Isilian weapons are also known to change and evolve as their wielder does, mirroring the strength gained by the swordsman over time, molding themselves to better fit the wielder’s style. Exactly how this phenomenon occurs is unknown, but duels between Isilian weapons have been proven to reward the victor with a markedly improved rate of magic absorption, for lack of a more precise term, while the loser’s weapon dims inversely. Thus, a duel of Isilian blades is not taken lightly by anyone.