Aggressive Nanday

About 2 months ago I rescued a Nanday from an abusive home. She is about 5 years old. When I got her she had an overgrown beak, long nails, and had plucked out all of her chest feathers. At first she was a little afraid but then became extremely aggressive. When you walk by her cage she lunges at you and then hisses. If I reach into her cage to change her food and water she tries to attack me and will sometimes grab onto my arm extremely hard and draws blood. I let her out sometimes to play with my jenday conure because that calms her down since the 2 like eachother. But while out she will fly at me and start biting me. She constantly draws blood if she happens to land on me. I feel really bad for her and don't want to give up on her but I am not sure if this behavior will change. I put gravel paper on the bottom of her cage so her beak has been filed, she has a ton of toys compared to the one toy she came with, and her feathers have almost completely grown in. She just has no trust for people so I am wondering if that will change over time or if she will never grow to trust me. She gets a blanket over her at night so she can sleep, has an avian sun light on her, always has food and water, and enjoys her toys.