My Nana was Euphemia, she died when I was little so I don't remember her but by all accounts she was a wonderful, formidable woman.
I'd never heard it but on a walk round a graveyard in Edinburgh I saw that it had clearly been a popular name in Scotland, and indeed she was Scottish.
I like it, but I think today it would be shortened to Effie or similar to modernise it. As Cherry said.