Pray it isn't the targetting beam for THIS weapon
The Nicoll-Dyson Laser concept, where a Dyson Swarm is used as a
phased array laser emitter that could destroy planet-sized objects
throughout the galaxy and beyond:
http://eg.orionsarm.com/xcms.php?r=oaeg-view-article&egart_uid=48fe49fe47202
Assuming there are ETI who might build such objects, this might be
yet another factor in the Fermi Paradox.
Nothing like being able to smite the galactic competition with your
own architecture and not even have to leave home to do it.