The Lost Art by Simon Morden
A millennium after the formidable war machines of the User cultures devoured entire civilisations and rewrote planetary geography, Earth is in the grip of a perpetual Dark Age. Scientific endeavour is strongly discouraged, while remnant technology is locked away - hidden by a Church determined to prevent a new Armageddon.
This is the world to which Benzamir Michael Mahmood must return. A descendant of the tribes who fled the planet during those ages-old wars, he comes in pursuit of enemies from the far reaches of space. The technology he brings is wondrous beyond the imaginings of those he will meet, but can its potency match that of the Church's most closely guarded treasure?
For centuries it has lain dormant, buried in a lead-lined tomb deep beneath the flagstones of a remote Siberian monastery. But it is about to be unearthed, and the powers that will be unleashed may be beyond anyone's capacity to control. Even a man as extraordinary as Benzamir . . .