Are you talking about a ipakita or just a girl? I thought you were talking about a ipakita 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 ipakita to answer either question.
for girl butt-kicking anime, I'd go with Black Lagoon or Kara no Kyoukai. For magic girl anime, I'd go with Puella Magi Madoka Magika or Tokyo Mew Mew. But I think my all around paborito is Black Rock Shooter :)