Silent Blade by Ilona Andrews — book slip

In a distant future, the Kinsmen—genetically and technologically advanced families—dominate the planet Rada with their financial empires.

Meli Galdes, from a minor family, was once engaged to Celino Carvanna, a powerful leader who broke their engagement, leaving her family in ruins.

With her rare talent as an energy melder, Meli becomes a lethal assassin, secretly protecting her family's interests. Now, her final mission is to kill Celino, the man who shattered her life.

But as she gets closer, old feelings resurface, complicating her quest for revenge.

First in the Kinsmen series.