Excelent find Andreas, that picture of a messenger
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I had (if i should) doubts about what kind of attire they wore, whether hard (armour) or soft clothes. In this case as shown, your badge would not be in the adequate material, but instead a textile one.
On the other hand, i would not agree that your example was fixed to wherever place by tying it with thread; besides being too soft to hold metal edges, the hole in the lower (V) corner would not be in the convenient position for thread binding.
I would bet on it to be riveted (nailed) to a hard material; leather, wood (a chest), metal ... whatever.