So, the story goes that my Great Uncle took this dagger off of a dead German officer during WWII. I have heard everything from a Captain to a General but I am not really concerned with the validity of the story but I am curious if there are any collectors on here that may be able to give me some information about what it is and as to the value of this thing. I have never seen another one like it and I always look at gun shows etc.
I am not a collector of Nazi stuff but I have had this since I was a kid and have always wondered what it was....

This is it in the sheath - it's about 20" long. The sheath is a little beat up but not too bad.

The handle has an eagle head carved into it (both sides).

Reverse of handle.

This thing is metal and is hanging off a ribbon wrapped around the sheath.

Sheath has the following stamped on the back:
JOHANN FROHLIGH
WIEN XV 1938

The blade is worn on both sides at the end.

Terrible picture but on the blade it says:
EWALD CLEFF
SOLINGER
And above that on the handle it says:
S.O.p. IV 453.

Close up of the ribbon.

Over all length of both.
Anybody have any ideas?
I am not looking to sell it at this time but I am curious if it has any value (other than sentimental).
Thanks.