Cool. Love the expression on her face. Wonderful perspective.
Feedback: She's got no grip. See my comment on one of your other works, "Damian Torn World" for how a sword should be gripped. The fingers also should not be too tight together, as the flesh spreads a little when gripping a handle with strength.
Also, based on the shadows, it appears as though her feet are almost in-line with one another; this is a no-no. Keep the toes pointed in the same direction, but move the right foot to the character's right by one shoulder-width.
Her's a diagram for a virtually identical karate stance: [link]
Oh, and keep the thumb directly above the index finger on the grip, but not on top of it. The second knuckles of the fingers should point as close to the same direction of of the leading sharp edge as possible.
The face looks great, and all the detail work is very well done. The problem, I think, is one of perspective. You have her upper torso leaning back, yet her feet are the same size, denoting her legs are on the same plane, which would indicate she is upright/and/or the camera is looking straight at her, rather than looking UP at her as the torso suggests. Hope that makes sense! And the rear leg should have the knee bent slightly toward us to enhance the aggressive stance. Tough pose! Figures in severe perspective a a real pain to get right, especially without a reference. Have you seen Genzoman's work here on DA - much more stylized, but great perspective action poses.
Just a quick crit, it looks superb except for that back leg- what you have drawn is a possible position physically, although with the sword it would be an uncomfortable one, and it looks awkward. That back leg should be facing the viewer much more... Also the sword isn't exactly right in perspective- as shown here it would be partially in the ground.