Welcome to AAPK T. Reuwsaat.
When you have time, perhaps you can add a picture of the "WR Case & Sons" logo from the blade?
I have never seen a Case knife with this configuration. Not saying that they do not exist.
We have many Case Knife pros here within aapk. Perhaps "Steve Pfeiffer" aapk handle (knifeaholic) and author of "Case Knives I.D. and price guide" will tune in and give you a very professional verdict.
I can inform you that you do have a "Pen" knife. The proper classification is: "Serpentine Sleeveboard Lobster.".... "A Lobster Pen Knife."
The beauty of genuine MOP was a favored handle material for the smaller pocket knives produced by Case. Pearl handled two and three blade pen patterns were classified as "Gentleman's Knives"
The first Lobster knife was invented by "James Crawshaw," a cutler and merchant who worked in Sheffield from about 1817 to 1850, he invented a new style of pen knife in the 1820s. An 1831 history described it as "the lobster knife." Unfortunately, Mr. Crawshaw did not acquire a patent.
Your "Serpentine Sleeveboard Lobster"
pattern is very rare and usually bring in the most resale price in the Lobster category. The pattern is one of the most elegant lobsters.
Winchester called the style the curved balloon lobster
It appears to also have a broken Master Blade. However, due to the fact that Lobster Pen knives are lightly built, they receive 'easy damage.'
It appears that you are a new collector? In this case, you may consider keeping it. Even due to its condition you, you will most likely never find another one. Once you receive a few dollars from eBay, the dollars and your historical very rare Case "Serpentine Sleeveboard Lobster." will be gone.
If you are not a collector, you may want to include the words "Serpentine Sleeveboard Lobster" within your auction description.
Thanks for showing your knife T. Reuwsaat. First Case Serpentine Sleeveboard Lobster I"ve ever seen.
It's always important to know what you don't know.