Straight Razor

[Mblossom]

I have an old straight razor give to me by my father who was 82 when he died 10 years ago.  It is very old, made in Germany.  It has ERUSTA Solingen-Germany on the blade.  Erusta Solingen on the handle.  The box has a "23" on it and also says: KOCH & SCHAFER and underneath that it says WALD-SOLINGEN.
I havethe certificate of warranty with: No 15923 on it.

Can anyone tell me anything about it?
Thanks