It's uncommon but familiar here in South Africa, where we have English, Dutch, German and French names all happily coexisting - and that's just the European languages! It's definitely feminine, and used less often than Isabel/le/la but it's there.
In fact, it features in a cute little poem that I won't inflict on you; called (I translate) Ballade of the Married Girlfriends, it is in strict ballade form and features the poet having afternoon tea with his auntie and answering her questions; they make him think further: What really did happen to Elsabe? What really did happen to Isabeau?
Elsabe, by the way, is a form of Elizabeth that I like very much; pronounced EL-suh-bee.