Aestra Khromys was originally a member of the Kabal of the Black Myriad, until she was enslaved and placed in a munitions factory for her refusal to bow down and kiss the hand of the Kabal's founder, Archon Vhloriac. Unlike most Dark Eldar exiled to such a place, Aestra wasn't driven insane by the monotony of the task and instead focused her attentions on creating weapons of such superior quality that her overseers couldn't fail to notice the skill of her craft.
Eventually she was purchased by the Kabal of the Obsidian Rose and given her own workshop and from there she placed her master plan into fruition, creating all manner of innocuous and concealable weapons ready for her audience with Archon Vhloriac. The element of surprise coupled with the mysterious failure of the Archon's Court weaponry gave her an easy assassination that propelled her to leadership of the Obsidian Rose.
"The Queen of Splinters" as she's also known, continues to fashion superior weaponry for her new Kabal and the Obsidian Rose are exceptionally well armed.