The following German 1926 advertisement has some extra information:
Vern deleted one letter of the last name which has an additional 'R' : Branner
The company acted both at Konstanz, a German city at the south seabord of lake Bodensee (Lake Constance) with a subsidiary in Kreuzlingen, located in Switzerlan at the northern seacost of this lake .... the state's border is crossing the lake.
Gustav Branner was in business as wholesaler of steelware ("Stahlwaren en gros").
So far no information is known, that Gustav Branner was a cutler, while several knife ranges with the corsair / pirate logo are showing up, being made under contract by various cutlers, such as
* swiss Army style pocket knives made by Wenger (Delemont in Switzerland)
* stiletto style switchblade knives made by cutlers from Maniago in Italy
* different pocket and sheath knives made by cutlers in Solingen / Germany.
Records from the German Patent and Trademark Office are stating the registration of the 'face' logo with with 'letter ears' indicating 'G' and 'B' in 1980, while the trademark was deleted in 2009.
Obviously the knife in question is of post 1980 origin and no WWII HJ knife.