Madness string 84091

Random mermaid
I know the accepted answer for all those really goofy-looking German swords is that they were novelties or ceremonial pieces never intended for actual combat, but then I remember that this is the country that not only invented the flintlock grenade launcher, but by all accounts actually attempted to use them in battle, and I have to wonder.

What always has four letters, sometimes has nine, and never has five? It's not a riddle. Just three facts that will confuse people.