Skyler is an assassin.
More specifically she is an impressive sniper, able to eliminate targets from a distance under extremely difficult conditions. Our introduction to her is in the recounting of an adventure of someone else, Skyler just showing up towards the end to remove an individual from living by making an important shot from a hovering helicopter. After the shot was taken and the target dispatched, she flies away.
In that encounter, we readers are told: "the killer was actually a much-sought after professional female assassin. In fact, the woman was of Italian heritage, but with her routine clever disguises, polyglot mastery of languages, and surgical alteration of her Roman nose, it was never possible to know for sure. Her given name was Angela Valentina Ferrara, but years ago she had become a full-time contract killer and forsaken her real name for aliases. Her current alias was Skyler, no last name. She also had a nom de guerre - Diego Gomez - a fictitious name created by her control agent. The invented Spanish assassin Gomez remained a mystery, a phantom of the files in the hands of the international law enforcement community. For her own security, Skyler was determined to keep it that way." So far "no one knew what she looked like or her true identity, except her control agent, Xavier."
When we meet her later in her own adventure, we are told "she had taken out oligarchs, powerful businessman, high-ranking government officials, "most wanted" terrorists, and rival snipers - a total of fourteen individuals in Europe, the U.S., Canada, and South America." We also learn "all of Skyler's targets in the past had been men. She hated men - how the hell could she not after what Don Scarpello and Alberto had done to her - and wanted to kill them all. But she had never harmed a woman or child, accidentally or otherwise. Nor would she ever kill a man in front of his family."
She definitely comes across to those learning of her exploits as a cold-blooded killer and at the time she pulls the trigger, she is. Later, though, was a different matter. "When the nightmares came - and they always did - she would quake with shame. With sweat pouring from her body and teeth grinding, she would see the faces of her victims, one after another. They always came through clearly, framed in the perfect circle of her sniper-scope with the crosshairs centered on the forehead. When she squeezed the trigger, the smooth, clear faces would explode in a spray of blood and she would gasp for air and leap up in her bed, covered in sweat."