Destruction of the planet Rahab (destroyed by the Arm of the Lord) which orbited between Mars and Jupiter.
There is an enormous debris field there now. 3i/Atlas is zooming on the ecliptic plane right through that debris space - a boomerang piece of Rahab debris.
On Mars, this would have been the compression of the magnetic field so deep that the discharge of force occurred in this spot, etching a canyon deep and long, in a matter of seconds. Note the "scalloped" edges of the "canyon." That is typical of lightning bolt patterns, not water erosion.
So your suggestion of a weapon is closer to the truth than a water canyon.
The explosion of Rahab (Mars was suggested as a moon of Rahab) compressed the Mars magnetosphere to a critical level - and changed its atmosphere forever.