To assail verbally or to discuss excessively is to?

The term that best fits the description of "to assail verbally or to discuss excessively" is "belabor." This word specifically conveys the idea of going over something in great detail and often to the point of tediousness. When someone belabors a point, they are emphasizing it excessively, perhaps repeatedly discussing it beyond what is necessary.

In contrast, while "berate" implies scolding or criticizing someone severely, it does not necessarily encompass the idea of excessive discussion. "Debate" refers to a formal discussion of opposing viewpoints, which may not always indicate excessive discussion, and "argue" is more concerned with presenting reasons or evidence for or against something rather than the element of excessive discussion. Thus, "belabor" aligns most precisely with the notion of overdelivering on a verbal point.