How is it pronounced? Since the Ermesinde you linked to was Spanish, I'd assume something like ehr-meh-SEEN-deh or ehr-meh-THEEN-deh, which I don't think is very pretty, but at first glance, I'd say URM-eh-seend, which I think is much nicer. With the latter pronunciation, it remind me of
Hermes. I think it would make a good name for a medieval duchess or nun who'd be an artist or patron of the arts, think
Hildegard of Bingen.