Fabulous art. Thanks.
Its good to note in the comparison chart at the bottom, the difference in size between the Void Bomber and the Idris. From early intel the Void Bomber is more heavily armed, but it is much smaller, and the actual size is much less than the measurements because it has all this flying armor surrounding it. It's actual height and beam is tiny compared to the Idris.
I think the design scheme here is similar to what we saw as the difference between German and especially Japanese battleships during WWII which were extremely heavily armed, and American and British battleships which were less heavily armed but had state-of-the-art damage control systems and were thus able to outmatch their opponents. The Iowa class battleship was the ultimate expression of this intense sturdiness built into the design.
Given the weapons the Vanduul have and the basic design of their ships, it looks like the very last thing you want is to be attacked by them. Rather, you want to attack them so they are out for the count immediately. It is that first few seconds of battle that will decide the battle in their favor. You can't allow them to hit you. And note if this is true, all the more reason to steal Vanduul ships and use them for privateering, since you want to use that design to attack from stealth. It's a "glass cannon" design that can't take a hit but doesn't need to if it gets the first licks in. It's the design of an aggressor, rather than a pacifier.