I almost exclusively use the word pussy in a sexual connotation and is also my wife's preferred term for her and other women's vaginas. And if I do use the word pussy to refer to someone being lame or weak I definitely have the image of a cat in mind, however as you stated I will likely just call them weak or lame. Maybe even pathetic. Yeah, I think pathetic is my favorite word to use in the situations that a lot of people use pussy in.