You can wear just one on the shoulder or to hold your scarf. Or you can use a pair and hang chains in between. I made some in bronze and in sterling silver with various enamels and stones.
Those a tough brooches and very useful when you have heavy fabrics.
The original one was found near the rhine and is supposed to have been made by a jeweler from the 7th century. The original was even signed by the guy
Wigerig was his name.