Are 당신 talking about a show 또는 just a girl? I thought 당신 were talking about a show but everyone else has been posting characters so I'm confused. But I'll go with Rin from Mnemosyne and I'll also go with that show to answer either question.
for girl butt-kicking anime, I'd go with Black Lagoon 또는 Kara no Kyoukai. For magic girl anime, I'd go with Puella Magi Madoka Magika 또는 Tokyo Mew Mew. But I think my all around 가장 좋아하는 is Black Rock Shooter :)