Thank you Michl,
The price was absolutely ridiculous, but Coburg deserved this lucky bargain.
I enquired about the specimen that was found in the ruins of Altbüron and was told that in 2012 Christoph Rösch made a book with this piece in it: "Altbüron. Die Metallfunde der 1309 zerstörten Burg. Archäologische Schriften Luzern 14, Luzern 2012. "