1. Some one could have made a bind(不太懂这个词,是否是DIY的意思?) for it. I have 3 Pelikans with custom binds
2. It looks like a pen made from a sheet of regular green stripe celluloid that was rolled at a right angle to a stamdard pen. It could have been a one-off job done by someone at the factory rather than a prototype.
3. That's an interesting specimen, thanks for posting it here.
The fact that there is the regular barrel imprint (Pelikan, Gunther Wagner) will justify an original attribution.
Custom binde don't carry that engraving AFAIK, and fakes usually are made to look like an orignal known and valuable model.