Brandon Sanderson: The Way of Kings (The Stormlight Archive Book 1)

Description

They came against man ten thousand times. To help them cope, the Almighty gave men powerful suits of armor and mystical weapons, known as Shardblades. Led by ten angelic Heralds and ten orders of knights known as Radiants, mankind finally won.
Or so the legends say. Today, the only remnants of those supposed battles are the Shardblades, the possession of which makes a man nearly invincible on the battlefield. The entire world is at war with itself - and has been for centuries since the Radiants turnedagainst mankind. Kings strive to win more Shardblades, each secretly wishing to be the one who will finally unite all of mankind under a single throne.
On a world scoured down to the rock by terrifying hurricanes that blow through every few day a youngspearman forced into the army of a Shardbearer, led to war against an enemy he doesn't understand and doesn't really want to fight.
What happened deep in mankind's past?
Why did the Radiants turn against mankind, and what happened to the magic