The outermost elements of this Dyson Swarm are emitting a powerful collimated beam which can cause considerable damage at a distance of several tens of light years
The power of a collimated beam is limited by the focus of the beam when it reaches a distant target. One way to improve this focus is to increase the effective aperture of the emitter; a very large object, such as a Dyson Swarm, represents a very large effective aperture if it is used to emit such a beam.
Dyson Swarms collect considerable amounts of energy from the stars they contain; if some of that energy can be stored, then directed towards a target in a different planetary system, considerable damage can result. In practice the outermost elements of the swarm, or the outer surface of a dynamically supported Dyson Shell (if present) become a phased array emitter. This allows a powerful beam to be focused on a distant target in another planetary system. This concept was first suggested by James Nicoll in the Information Age, and is known as a Nicoll-Dyson Beam for this reason.
Nicoll-Dyson beams are routinely used to propel laser-sail craft at interstellar distances, and have been used to send messages to distant locations. Several messages have been sent by Nicoll-Dyson arrays to locations outside the Terragen Sphere, particularly to the closest High-energy emitting civilisations which have been detected in the Milky Way galaxy.
Nicoll-Dyson arrays can also be used as weapons; severe damage can be inflicted on a planet's surface or on a megastructure at great distances. They have, however, rarely been used destructively; a number of beams were fired during the Oracle War, for instance, but they are regarded as weapons of last resort. If a beam is fired, this results in significant destruction in a distant system many years later - during the intervening period wars may have ended, treaties may have been signed, and the political landscape may have changed- but still the beam is on its way and cannot be recalled.
Using powerful telescopes including the Argus Array, evidence of high-energy conflict has been observed in several distant galaxies; the use of Nicoll-Dyson beams has been confirmed in a number of cases, and is suspected in others.
There are today many Dyson swarms and similar constructs in the Terragen Sphere, many of which are not part of the Sephirotic Empires such as those built by the Panvirtuality and the Efficiency Maximisation Paradigm. If interstellar relations ever decay to the point where Nicoll-Dyson beams are used en masse, the Orion's Arm Civilisation could be damaged or even destroyed in a very short time.
Some commentators relate this to the mystery of the Great Toposophic Filter and the disappearance of so many xenosophont empires in the past.