Yay. I am so so tahnkful she found you. I am also glad you did not give her mice (the fur could have been a major problem for her in a weakened state) I was going to suggest cutting some fresh chicken or beef into stir fry strip size for her.
In our traditions and beliefs, Hawks are messengers. Hawks have been known to intervene and cause drivers to avoid unseen road hazards. By our beliefs, she came to you with a message or teachings if you will. I am sure if you think on it, you will find that message/teachings
The hawk, specifically the Redtail is a strong totem for you. Like me, you will see them often I am sure.
I found Nikki. a redtail, under an orange tree when she was about the same age as Frightful, she had been shot by some kids with BB guns and her wing was damaged. Back then, you did not dare call , a vet or anything like that because they would just put them down and be done with it...most still do. So, I climbed off my horse, walked over to her and she was flared up like your Frightful, but I told her I wanted to help and I picked her up...she never offered to bite me so I climbed back up on the horse with her and rode home. My Grandfather and Great Grandfather help me get the BB out, stitch her up and we used popcsicle sticks to straighten the broken bone on her wing. She became my pet and companion even after she healed, she would never leave. She followed me horseback riding, she was always near me...until she died when I was around 17 years old. She has a good healthy life and I removed one her talons after she passed and kept it...I have it to this day. They are amazing creatures.
Frightful taking fluids and eating a fleshy mouse is a good sign indeed...keep us updated please.