According to documents archived on HNN (1), Asana was a participant in "Project Nidus", an apparent Omni initiative geared toward creating nanite-infused warriors. Each warrior is said to wield an Ancient, a mythical weapon forged by GAIA in the heart of a Reactor. It is rumored that Asana is currently tasked with guarding high-ranking Omni officials and keeping watch for other Nidus initiates at large in Atlas (2).
Years of nanite exposure have imbued her with the power to create protective forcefields and withstand brutal attacks. It also turned her purple. But don't bring it up, unless you'd like to be black and blue yourself.
Asana knew the Reactor could repair any scar, but she kept the one on her hip to match the one on her heart.