You can only see this dress in one scene, when Diana enters a German ball during an undercover mission. However, it is very beautiful and attractive while being a huge contrast to her warrior look. By the way, she seems to wear her normal boots underneath the whole time. In addition, the sword is hidden underneath the dresses neckline. I guess the movie costume is made from silk, but I did not want to spend that much and decided to buy some lightweight fabric that was on sale for 2 Euro. The total amount needed was four and a half yard. In top of this, I used a zipper and some hooks from my stash. Although the dress is far from perfect, it is very comfortable and easier to handle than real silk. The pattern was made by me, too. Thanks to Jonathan for taking the photos. You can see his work by visiting his photo album. Editing by me.
I did her armor, too, which you can find here.