The following stills are from a 1967 educational/instructional film about contour drawing. This Eberhard Faber Blackwing still has the black-banded ferrule:
If you look closely, you’ll see that this pencil also has a custom stamp: “M. FLAX, INC”.
The only custom-stamped Blackwings I’ve seen prior to this were from the Boston Athanæum, which were some of the last Blackwing pencils ever made. It’s possible that the pencils could have been stamped elsewhere, but as far back as the turn of the twentieth century the Eberhard Faber Co. was custom-stamping their premium pencils, such as the Van Dyke.