The only instruments making a decorative look on a wall are, in my humble opinion, string instruments. I have hung my old guitar, banjo and balalaika (or should it be hanged? with a noose around the top of the neck), because I don't drag them out of the house; I can easily take them down for playing.
All other instruments like flutes, fifes, mouthorgans I keep in their cases ready to go. They are too small for a well looking hanging.
An akkordeon I would only place on a shelf for display.

Aloha ohe!
Wilfried