This name just looks very, very confusing. With my knowledge of French (about "Seconde" or "Première"), Étienne has always appeared feminine to me, even though I know it's a masculine name. Étiennette looks like it has two endings traditionally used in French feminine names: -enne and -ette, one right after the other.That's likely why this name has fallen out of use. (Though Étienne is still fairly common, go figure.)