i will include a site with some info that may also be of help, please do not give up on kitty without trying everything possible. can you separate the cats when your not at home?
also try FELIWAY a room spray that is all natural and helps to calm kitties...its also very useful for trips to the Vet or anything that causes them to be afraid. its available at most Vet clinics and and good pet shops....
http://www.vet.cornell.edu/fhc/healthinfo/brochure_aggression.cfm
They might be fighting, they might be playing. If they are fighting, they should not hold back from doing it in front of you as well as when you are not home -- kitties into dominance fights do it whether Mommy is standing right there or not. I'm not sure I would have a declawed cat and a cat with claws in the same household, since they will of necessity even play differently, much less fight differently, than each other, due to the disparity in weapons.