story identification - Woman who gets trained by a soldier; dead soldier returns as a ghost; bird/raven people

I am writing in hope that someone might be able to recognize a book series that I read some years ago. Can't find anything that resembles my memories of it. From what I recall it contains a strong female lead. In the beginning of the book, she gets training from a soldier, older than her, and they fall in love. The man gets killed and returns later in the story as a ghost.

The female has got magical powers and fights an evil old man, from whom she must escape and travel distant lands. I think she might have had some magical animal with her (a big cat, or something similar) but again, this is very vague in my mind. I recall a character named Sarah, and a man that Sarah used to be together with called Alvar (?), whom the female lead eventually ends up with at the end of the story. I also remember a character of some kind of bird/raven people (maybe she is even called Raven?), who is betraying the lead and her company to the men of the evil old dude. I think there are some problems with her people or something about wings or the ability to fly that makes her do it.

Not very much to go on perhaps, but it someone recognizes anything that might help out I would be most grateful!