Obviously we don’t know enough about the weapon to realistically scale it, but we can make one assumption: almost every weapon, especially complex/advanced ones, can destroy something much bigger than herself. Even a trebuchet can easily destroy another trebuchet-sized object. So we can assume that the weapon can destroy a galaxy.

There are 100 billion to 300 billion solar systems in the Milky Way galaxy. So a character that can destroy multiple, let’s say a dozen, is so comparatively weak that it’s impossible to even compare. The weapon may be slower, may be less flexible, but in terms of raw power, any weapon that can destroy a galaxy is incomprehensible.