Different cats can produce slightly different dander - one of my cats makes my husband sneeze like crazy, while the others only bother him a little bit.
If Sasha is a very fastidious cat & always grooming herself, she might have more dander on her - it comes from the deodorizing component in her saliva. I think that's why Felixia bothers DH more.
If it's really bad, it might be worthwhile to rinse her in warm water every couple of weeks to cut down on the dander. That's what my allergist recommends - he says you don't even need to use shampoo, that just rinsing thoroughly with warm water works just as well. Or you could try some of the allergy wipes or solution sold in pet stores for use on cats.