In my opinion is a north Italian storta, or coltella, I am 99% sure of this, pommel does not belong originally with the sword, the "classic" pommel for this tipe of sword is the one mounted in the example posted by @Cerjak.
About the guard, could be a local style, it seems that the "base" is the classic storta guard with added extra arms on the side.
Here you can see a storta made in Caino (near Brescia).
Also Decorations on the blade confirms that has been made in Italy.
Here you can find some additional infos about this tipology of sword.
https://www.hema-minsk2019.org/base_...ibition-part-3
About the SZ mark...yes could be an arsenal mark, considering this is a infantry weapon, very common and cheap. On the other hand there are many examples about initials of the maker in Italian blades.
Cheers
Giovanni