Angels aren't necessarily good and sweet, there are some pretty mean angels in the Bible. So it's not like they are all perfect, in a long white gown and better than mere mortals. I don't think it denotes perfection at all.
I personally think it's okay as a name. I know one and it works on her.
I always think it's weird when people say someone is 'out of their league', especially for physical reasons. There are so many attractive people out there who have unattractive partners. Maybe you meant because of her looks and personality.