Unlike the previous posters, I find "Henna" rather comedic, juvenile, and unprofessional. Of course, it is moderately better than "Hannah"... but that is not difficult to do.To my knowledge, the Henna-dye is commonly known in our English-speaking countries, to the point where an association and tagging would be initiated.Regardless if you remove the beginning "H," a splendid name of "Enna" is born.
This is a name I would seriously consider to use if I have a daughter some day, because it's both a beautiful, kinda unusual name, and it's a feminine form of Henry which is the name of my grandfather.