I know... (that's why in my mother tongue her name has been translated into something that means "eagle claw") It's weird... Raven are more associated with knowledge and wisdom than eagles (which are bird of preys, more associated with war, nobility at least in my mind...).
Maybe her patronus was an eagle, or she was an animagus who could turn into one?

Yeah, except why not a raven, or a black bird at least. Or even just a dark colored bird. Raven are actually very smart. They learned when the garbage truck comes in my neighborhood.

Yes, Ravens are very smart (and other corvids as well, that's why I'm happy to have a crow as a patronus while a lot of people don't like them and would consider it to be a lame patronus) and it would have made sense for Ravenclaw to have a Raven as her symbol.
They can also imitate sounds, including human speech (a bird where I lived when I was in England used to come close to windows and to imitate the sound alarm clock on the morning... It took me weeks to realize that this sound was not coming from one of the neighbouring flat but from a bird outside! It was so irritating! And I'm SURE it did on purpose, since it did it only when some people were sleeping!), recognize human faces, use basic tools, communicate between them... Plus corvids are not afraid to attack bird of preys to protect themselves and their nests (I've seen carrion crows attacking hawks, falcons and kites a lot bigger than them and winning against them!).

I would said that Rowling may have used an eagle because they often have better reputation than Raven and considered as "noble", but then she would not have used a badger for hufflepuff... Maybe she had decided to use an eagle as her symbol before choosing her name, and later did not want to change the symbol?

Perhaps, but seriously, If you leave a trash bag out on tuesday of thursday, the ravens and crows will come and tear them apart for food. If you leave them out in wednesday, trash pick up day, they will not come near, even if the truck isn't there until 3 o'clock.

I got a Thestral