I like
Hildegard a lot. I think -gard is a strong, stately element to a name. It is a very strong flavor, though, and your instinct on a plain name with it is good.
Anna Hildegard is a really nice combo.
Anna is a very light, almost transparent name, and I think that combo is great.
Mary has too much flavor for me with it.
There aren't many names as light as
Anna. Maybe
Jane Hildegard?
There are a few short names that are still flavor-rich whose flavor is complimentary.
I think...
Eva HildegardYlva HildegardVera HildegardFreya Hildegard
Names with Vs apparently.