Updated with a newer version: better contrast, more detail in the face and improved (I hope) perspective on the sword.
Practising four-tone composition may lead to unexpected results sometimes! This lady just jumped out of my scribbles all of a sudden and demanded that I at least complete the figure and refine it a bit. Oh well, can't say no to a woman (especially one with a sword and a whip).
Would ya say she's a demon or an angel? Can't quite decide (although I do tend to think of her as more an angel than a demon. Well, maybe a battle angel. With a whip, yeah...). She looks like something out of Diablo or Heroes of Might and Magic to me, although it's not intentional, and besides it's been a long time since I played those games, and I may have forgotten everything.