Hi schubert and welcome to the forums,

www.nifty.org has a smallish > Lesbian > Battle category,
though I think they are not really stories, just brief scenes.
http://www.nifty.org/nifty/lesbian/battle/index.html

Other than that, you might have fun with some fanfiction from the Xena Warrior Princess ‘conqueror’ alternative universe genre. Though... um... if they have a plot, they usually seem to end in the inevitable soulmate harmony anyway.
http://www.academyofbards.org/conqalt.html
http://www.academyofbards.org/annals.txt

Enjoy!