My mare is EXTREMELY leg sensitive. She was very badly abused when she was younger, so ANY pressure from the riders legs sends her through the roof. Well, that's how she WAS. I have been working with her on it for the past 5 months. She can be ridden bareback now, with not much of a problem. Every time I ride, I just make sure I know where my legs are at all times, and keep my leg on her, but not squeezing. If that makes sense? She knows its always going to be there, but it wont hurt her. She has realized that when I gently wrap my legs around her, and gently apply pressure, it doesnt always mean go faster.
Sorry if that sounds like a jummbled mess, I don't know how to explain it, but it is something that CAN be fixed. Or atleast tollerated on the horses part.