The stories of "Lady" Szasa are as myriad as her titles: The Hurricane of Death, Bandit Killer, The Human Typhoon, God Killer, Liberator of Stony Cove...The list goes on and on.
What most stories agree on, however, is her raw magical power. They also all agree on her mercenary nature: she takes a job, she does the job, and she gets paid. It's well known that even Szass Tam knows not to cross her.
In reality, most of the rumors have a shred of truth in them; she is mercenary, but she learned to be after a pair of cities at war with each other both hired her, and then after she did their job, tried to kill her. She is also an insanely dangerous Sorcerer.
Szasa is not, in fact, a noble of any kind. She's of Vistani blood, which drives her to wander Faerun, taking in what work she can. She has a grown son that she had at a young age who is also an adventurer.
The story about Szass Tam is true though; he saw what happened to one of his rivals who tried to doublecross Szasa and wisely decided to never attempt such a feat.
Currently, she's been stuck in the Moonsea region for a while, having been put on a ship by the Queen of Cormyr and being paid to "not be on the mainland for a while".
Szasa is killing time wiping out any bandits in the region, using fire, lightning and other magic to crush, maim, and kill.
She knows it's just a matter of time before she's needed for a real adventure, and she's just keeping busy in the meantime.