This is the original Walburga! Some notes from its wonderful maker (edited for showcase format):
This is Walburga the Wappenrock (German for tabard/surcoat), which does not follow any real historical garment but is my own medieval Europe (and Legend of Zelda) inspired fantasy design.
As far as my research showed, Romans didn't use these types of garments for identifying purposes. In medieval times in Europe they were used for displaying the colours or heraldry of the kingdom, etc.
It's also a very simple shape, that can be made in various lengths; comparatively short like I did here, or almost reaching the floor. As for width, it goes from shoulder to shoulder and is supposed to be open at the sides. I decided on a triangular neck opening here, so that the tunica peeks through and the shoulder seam does not become too narrow/it can lie closer to your neck.
There are also some checks in place to ensure that your head still fits through, even if you change the opening angle (the default triangle is calculated to have a golden ratio, as well as the bottom triangles). The bottom part is split (can also not be cut) for mobility (though honestly, at this length mostly for style). Since there is no way to add a seam/hem allowance like this, I decided on finishing all edges with not-quite bias tape which looks quite nice.
You can also see my first attempt at appliqué here :D