but do readers actually know that's where they came from without either an explanation, or at least some education in Norse mythology?
Hmm well maybe it's different where you are but here (UK) at least I'd say most people could tell you a least a little about it ( hey we got invaded by the Vikings and Saxons how many times? We learn about it at school. My boss says a Norse toast every time he has a pint) So most fantasy readers here would have a rough idea at the very least. And tbh, every one of the fantasy readers I know has a reasonable working knowledge of the basics of Norse mythology.