Fantasy Novel with Alternate Arthurian Mythos, Knights Magic Sentient Swords, set in Alternate Late Middle Ages

Question

I'm hoping to finish a book I borrowed from a library in college half a decade ago, but can't remember its name. Alas, I only got halfway through it before I had to return it, and then I couldn't remember its name.

The book features a few knights from a British (English?) Order, who have magic swords. The swords are imbued with power through the sacrifice of a living person. If I recall correctly, the book's major protagonist wields a sword holding the soul of Genghis Khan?

The main setting detail that hooked me is that it is an Alternative Arthurian mythos: Mordred is the one the modern kings claim descent from, who freed the people from "Arthur the Tyrant".

The plot centers around a discovery of someone making new "magic swords", which is discovered when a young Mediterranean fisherman (more of a boy, really, a side protagonist/view point character) trawls one up in his net.

Answer 1

Joel Rosenberg's Paladins

Every schoolboy knows that Mordred the Great defeated King Arthur the Tyrant in the twelfth century, and Mordred's heirs had preserved the British crown through the Age of Crisis, and extended its reach halfway across the globe. By the 17th century, much of Europe, Asia and the New world was ruled from Londinium by the the kings of the Pendragon dynasty, protecting the Crown against the still-powerful Holy Roman Empire as much as the onset of the Dar Al Islam. The ragged band of outlaws that had been created as Mordred the Great's bodyguards had, over the centuries, become the paladins of the Order of Crown, Shield, and Dragon, dedicated to the Pendragons, each one taking the vow of ''Service, honor, faith, obedience. Justice tempered only by mercy; mercy tempered only by justice.''

But knights of the Order had more than vows to preserve the Crown. During the Age of Crisis, the Great Wizards had forged live swords to be weapons of the Order knights. Weapons of such power that could be trusted to no lesser mortals, because White swords held the souls of saints, while the Red swords imprisoned the souls of those who were anything but saints, and in the wrong hands, Red swords were capable of unspeakable destruction.

The art of making live swords had perished with the Great Wizards at end of the Age of Crisis.

Or so everyone thought.

But now, as the Crown, the Empire, and the Dar Al Islam sit astride the world in a precarious balance, three knights of the Order have discovered a brand new, previously unknown Red sword which has been very recently forged.

Worse, the tortured soul imprisoned in the sword remembers that it was only one of many which were cached in the hold of a mysterious sailing ship, origin unknown, and destination uncertain....

Found with a DuckDuckGo search for "arthur the tyrant". It has a sequel, Paladins II: Knight Moves