Parental dilemmas

My eldest daughter, AKA the Princess, is such a sweet, caring, gentle kid. She is truly a princess, and even though she think she's really tough, she's a buttercup compared to other kids. She doesn't look frail or small or gentle - she's tall for her age, she's strong - VERY strong from years of gymnastics (I mean her stomach is like IRON - she is ALL muscle). But really - she just doesn't know what to do when somebody picks on her. I had to help her out recently with this kid, 4 years younger than her and half her size, She just did not know how to handle him. And I am constantly faced with this dilemma. I mean, I'm a big believer in standing up for yourself, NOT letting people climb all over you, saying everything that needs to be said. But how do I get across to the kids the fact that I love how they are so sweet and loving, but they do need to get angry once in a while? I tell them - if someone picks on you, calls you names or curses - I, your mother, give you my express permission to say the same things back to them. If someone hits you, I permit you to hit them back. DON'T turn the other cheek - get even! On the playground, only you can stand up fopr yourself. I know it sounds harsh - but I don't want them feeling like they don't know how to handle things - I want to feel easy that they can defend themselves.