It's their flagship? Interesting what that could possibly mean.
Presumably that it's state-of-the-art Romulan technology and that it's an honor for the flagship to test the new plasma weapon and/or the cloaking device.
However, I can't see what's so "glorious" about their mission.
Essentially they are shooting at sitting ducks (the United Earth outposts on asteroids).
I assume that the Romulans (like the Vulcans) felt it extremely offensive that some aliens were monitoring their "private" affairs, thus the whole mission wasn't to start a possible new war but simply remove something the Romulans considered a thorn in their side (but then, that's something Spock should have been able to understand and mention it...