WARNING: The following article contains spoilers from Shadow War: Alpha #1, on sale now.
In the opening to Shadow War: Alpha #1 (by Joshua Williamson, Viktor Bogdanovic, Daniel Henriques, Mike Spicer, and ALW's Troy Peteri), during a practice match with her son, Damian Wayne, Talia managed to avoid a blow that he was certain would hit. When questioned how she accomplished this, Talia said that it might be because Damian talks too much when fighting.
While this was meant to be a joke to play with her son, Talia might not be too far off the mark. Damian has a habit of bragging too much when in a fight, a habit he repeated during the practice match. While it's typically expected for Robins to be chatty during a fight, in Damian's case it might hinder how effective he is as a fighter. If so, then he might become a better warrior if he could learn to shut his mouth.
Damian has always placed himself on a pedestal. First as the "Heir to the Demon" then later as the "Son of Batman" While those are both impressive titles, the people he usually goes up against are either not impressed by them or hate him for it. Sometimes a combination of both. Yet Damian is also someone who likes to brag about his pedigree and as such, it can cost him his ability to fight at his best when he's also contemplating how to sound impressive.
As Talia pointed out, this costs him time. Granted, in the form of mere seconds, but the enemies Damian often faces are typically warriors who can use seconds to seize the advantage in a fight. If talking during a fight costs him those precious moments, then it poses the question: How much more dangerous would Damian be if he simply stopped talking when he fights?
First, consider that the times when Damian has fought at his best were when he focused on the fight and didn't waste time with words. The best example comes from his last fight with Connor Hawke. Damian said very little during the fight and even though he was still in recovery from previous injuries, he managed to fight so well that he garnered applause from other professional fighters, many of whom were professional killers.
If he could do that while not being his usual pompous self, then it's not too much of a stretch to imagine that he could be one of the best fighters in the DC Universe if he learned some humility. Considering Damian is already leaps and bounds ahead of the other Robins in terms of training at his age, this in addition to the various mentors he's had over his life makes him a singular kind of fighter.
As an individual, he is also the closest personality-wise to Batman. It would make sense that, unlike his predecessors, Damian actually functions better when he just focuses on what he's doing and remains grim and silent. In addition, Damian has proved he could defeat Talia in combat when he was ten and did not talk as much. If so, then if he just shut up when he needed to defend himself, then there would be very few fighters in the world who could beat him.