In The Shadow Of Lightning by Brian McClellan

 

Demir Grappo should have lived a charmed life.  He was the son of one of the ruling families of his country and he was a Glass Dancer as well.  Glass is the material that fuels the economy and gives its wielders abilities others don't have.  But Demir, as a general who won the most fabled battles, grew sickened of war and his role in them and left his family and its wealth and power.  He became a grifter, moving from town to town as his cons are discovered.

When his mother is assassinated, Demir returns home.  He finds a country on the verge of ruin.  Godglass and all its power is running low.  Sensing that the country is getting weaker, its most feared rival has declared war.  Demir reluctantly agrees to head up the battle for his country.

Tessa is a glass master.  She has the plans to create a new source of godglass, one that works with lightning to give it power.  She is captured and enslaved at a glassworks.  When Demir rescues her for her knowledge, a spark lights between the two.  Can they unite to save their world?

McClellan is known for his work in the epic fantasy genre.  The world building in this novel is well done and the characters are interesting, especially Baby Montego, Demir's best friend and a renowned fighter.  There are rival families trying to gain power and the loyalty of men to Demir and their country as it faces a challenge that could end it.  This book is recommended for fantasy readers.