Well done, Jean.
Paperweights are nearly always a pain to interpret. I think the artists must be affected by the small space to sign in.
As far as I can tell "Mann? Z" or "Mann? 2" or perhaps "Mam? Z" or "Mam? 2" seems to be what I can make out. Unfortunately none of those apparent starts leads to an artist I know of. Let's hope others can do better. One final guess "Manny Z"
Ross
PS. Attached a worked on picture of the signature that I was using to try and identify the name.