I don't know about others, but I find that modding CK2 is where at least half of my enjoyment comes from. Obviously, when CK3 comes out, I plan to mod away. To that end, I wanted a border to match the traits they previewed. I figured that I'd post it here in case anyone else wants to copy it. When creating your own trait icons, it's probably best to use this as a value layer on top of your image layer.
FYI: This layer is a 114x102 pixel png.
FYI: This layer is a 114x102 pixel png.