The Church of England is considering scrapping the currently legal requirement for reading marriage banns in the run-up to a wedding (see here). The word banns these days exists only in the plural, but the singular (in the form bane) was used before the 16th century. It is related to the word ban, which has a Germanic root, but which came into English via French. The French ban was originally a “proclamation, publication, summons, proscription, outlawry, banishment, assemblage of military vassals” (OED). In early use in England a ban was generally a summons to arms. Ban’s meaning as “a formal and authoritative prohibition” dates from the 17th century.
The word banal is also related to ban. Banal originally meant “of or belonging to compulsory feudal service”, and, because there was an idea inherent in this that the whole community was affected, the modern sense of banal, namely commonplace, arose.