"Nightwatch does, in fact, have an "heraldic banner" which is in the form of
its black uniforms."

Err...I hate to correct you, but Nightwatch members do NOT have black
uniforms. Many of them wear armbands, but others do not. Julie Musante did
not wear an armband. Neither did the snitch in C C who turned in the Narn
cruiser in "Fall." B5 security members were given the arm bands as part of
their uniform, indicating that they were serving Nightwatch in an official
capacity, the same as you'd give a badge or ID to someone working for two
agencies. There are and can be others who are part of Nightwatch who don't
wear the arm bands.

Also, it's not "an heraldic." It's A heraldic. You only use AN if you can't
hear the H sound; if you can, then you use A. As in "An hour" and "A horse."
Similarly, the use "an historic" is also incorrect.

jms