Schlock Mercenary X: The Mundivore, or, "Eat it"

[factotum]

Or the Pa'anuri have another gun.

This one was the size of a solar system, I seriously doubt they have a backup--although, as my previous comment proved, I'm obviously not the best at guessing this! However, in this case the note "The most powerful (and longest ranged) weapon for 12 million light years in any direction" certainly implies this is the only one they have, and since that's not an in-universe comment but something added by the author, it would not be a great move if he proves that to be untrue at some point.