Does it look anything like this?
View attachment 2865178
This mark was used by David Everts, Stahlwarenfabrik, Solingen. The company was founded in 1806 and registered in 1886. The founder's grandson, Julius Everts, ran the company from 1900 to the early 1930s. He acquired the lance and banner trademark sometime during that time. In the early 1930s Julius sole the company to Ludwig Groten, a well established pocket knife maker. Groten continued to use the lance and banner mark until into the 1980s. I would expect he used various iterations on this theme and your knife is probably one of them??
edit: just checked Bernard Levine's forum, someone beat me to this answer.