The Stormlight Archive by Brandon Sanderson (Books 1-2 in the Series)
The 2-book set of mass market paperback novels includes the below titles:
The Way of Kings (ISBN 9780765365279): I long for the days before the Last Desolation. Before the Heralds abandoned us and the Knights Radiant turned against us. When there was still magic in Roshar and honor in the hearts of men.
In the end, not war but victory proved the greater test. Did our foes see that the harder they fought, the fiercer our resistance? Fire and hammer forge a sword; time and neglect rust it away. So we won the world, yet lost it.
Now there are four whom we watch: the surgeon, forced to forsake healing and fight in the most brutal war of our time; the assassin, who weeps as he kills; the liar, who wears her scholar’s mantle over a thief’s heart; and the prince, whose eyes open to the ancient past as his thirst for battle wanes.
One of them may redeem us. One of them will destroy us.
Words of Radiance (ISBN 9780765365286): Brandon Sanderson’s The Stormlight Archive sequence began in 2010 with the New York Times bestseller The Way of Kings. Now, the eagerly anticipated Words of Radiance continues the epic story and answers many of your questions.
Six years ago, the Assassin in White, a hireling of the inscrutable Parshendi, assassinated the Alethi king on the very night a treaty between men and Parshendi was being celebrated. So began the Vengeance Pact among the highprinces of Alethkar and the War of Reckoning against the Parshendi.
Now the Assassin is active again, murdering rulers all over the world of Roshar, using his baffling powers to thwart every bodyguard and elude all pursuers. Among his prime targets is Highprince Dalinar, widely considered the power behind the Alethi throne. His leading role in the war would seem reason enough, but the Assassin’s master has much deeper motives.
Expected by his enemies to die the miserable death of a military slave, Kaladin survived to be given command of the royal bodyguards, a controversial first for a low-status “darkeyes.” Now he must protect the king and Dalinar from every common peril as well as the distinctly uncommon threat of the Assassin, all while secretly struggling to master remarkable new powers that are somehow linked to his honorspren, Syl.
Brilliant but troubled Shallan strives along a parallel path. Despite being broken in ways she refuses to acknowledge, she bears a terrible burden: to somehow prevent the return of the legendary Voidbringers and the civilization-ending Desolation that will follow. The secrets she needs can be found at the Shattered Plains, but just arriving there proves more difficult than she could have imagined.
Meanwhile, at the heart of the Shattered Plains, the Parshendi are making an epochal decision. Hard pressed by years of Alethi attacks, their numbers ever shrinking, they are convinced by their war leader, Eshonai, to risk everything on a desperate gamble with the very supernatural forces they once fled. The possible consequences for Parshendi and humans alike, indeed, for Roshar itself, are as dangerous as they are incalculable.