Hi David
I am glad for your mutual interest in trying to find how things make sense. I was precisely going to ( somehow ) sugest what Flavio has just brought up in a clear manner. These pieces not be for hanging against the body, weapon like, but for decoration or cerimonial purposes, or even for trading as money or the like.
In other words, to be held in hands, with a double face look, thus with trimings in both sides. This not excluding that the "window" was to show off the contents, as you sugested, to proof that the thing had some added value. In above example 133 the blade is much much smaller than the sheath. BTW, I must say that in my piece, the scabbard collar doesn't fit into the handle slot as a functional weapon should do.
Here's another example i found in the Net, a bit more modern, but of a similar situation ... i still think my piece is a bit older
http://www.hermann-historica.de/aukt...db=kat48_1.txt
Thank you so much for the precious input, Flavio.
fernando