I suspect there are many different versions of this particular compass.
I have one that looks very similar to the OPs but that would be where it stops.
Mine was marked with the broad arrow stamp as well and the body is similar but with different markings around the base. They indicate the points on the compass as well as rough degrees. It has a lid lock and a device on the lid to lock the dial in place when it closes.
It has three different indicators on the dial. A gold colored arrow, degrees in five minute increments and degrees in minute increments.
The cover face is marked VERNER'S PATTERN VIII.
The back is marked
1918
E. KOEHN
Geneve Suisse
No 154239
\'/
The dial on it works and is for the most part legible.
The rubber pad is missing from the base.
The lanyard ring is also missing.
I was going to send it to a place in the UK where they repair these and have it restored. The problem is it costs more to refurbish one than it is worth.
This compass owes me nothing. It came from my mother, now deceased, that got it from her brother. All I know about my uncle is that he served in North Africa and Italy. He took a few small things home with him but nothing overly special. Just this and an Italian bayonet he found in a slit trench on a belt still in its scabbard. The soldier that lost it was nowhere to be found.
I think I will leave it as is. I don't want to carry it around the bush because as sure as God make little green apples I will lose it. I have a Viet Nam bring back M42 compass that will do everything I want it to do. It is in mils, has a ###tant and level bubble. I dropped it this fall and broke the glass. Now I have to find a good place to get it replaced and refill the nitrogen.