There were a few "Ern" cutlery manufacturers in Solingen Germany. The largest & most prolific was Carl Friedrich Ern or "C.F. Ern". Their main trademark logo was an Eastern Crown above a Scimitar, but they registered at least 100 trademark names. In business 1874 to late 1990's. What are the markings on your knife ? Pattern is known as a "Springer". Would be helpful to know when this pattern was first made. Maybe there is a registered patent in Germany and this would give a date. kj
During board of the Third Reich the firm was not engaged in manufacturing of knifes, but on HJ a knife there was mark ERN, Solingen and a sword with a crown. Pocket knifes also were branded by trade mark ERN. To 1940 firm represented only two trading marks: “a crown and short asian sword” and “an eagle with the snake”.