Raindrop (2013)

From publisher blurb:

The name of Varelina Fetema Sara was infamous among law enforcers and government officials throughout the Imperial Alliance. A human born to a gevet mother, she was a notorious spy. A gleaner of many secrets, she long evaded the pursuit of Protectorate Peacekeepers, Imperial men-at-arms, and even Janissaries. The many powerful figures preyed upon by Sara pointed fingers at the Dominion, the Phoenix Guard, and the Confederacy as the powers behind the spy’s activities. All have denied any connection to the woman. She may have worked for all or none of them. A few even claim she served the First Ones or Xon. Some wild rumors say that she still gathers information for the Isle of Silk and Iron in preparation for an invasion. Whatever the truth, part of the spy’s success was due to the properties of Raindrop, a powerful combined sword and shield disguised as a simple umbrella.