Oh, sent a request to some calc members to have the light beam thing calced if possible.
Here's the full quote since I noticed I quoted wrongly the first time, when Kiritor reacted to and fought against Fanatio's light beam. This is the exact post I sent to the calc members (half of it anyway).
- - -
Eugeo stared in terror at the Heaven Piercing Sword gripped in the knight's right hand as it seemed to gradually adjust its angle towards the two of them.
. . . Upon turning his head, his partner continued with a slight smile visible on his bloodstained lips.
"You didn't get this far because you hated integrity knights, right? You wanted to take Alice back, you wanted to meet her again… you're here because you love Alice, right? That feeling definitely won't lose to her justice. I'm the same… I want to protect the people in this world; I want to protect you and Alice and even her over there. So there's no way we can lose to her now… isn't that right, Eugeo?" Kirito's voice was calm despite the desperate situation. The black-clothed swordsman with many mysteries surrounding him nodded once more with a smile and looked forward.
That was the exact moment the Heaven Piercing Sword fired what was likely its final and greatest beam of light.
It was a gigantic spear of light, large enough to fit all of the light rays it fired thus far and more. It was like the Holy Spiritual Light itself, personally thrown by the goddess, Solus, to drive away Darkness God Vector during the world's creation, had swooped to incinerate all that exist.
Kirito's black eyes flared wide open and were gleaming with overwhelming resolve. His voice that recited the final verse was filled with an unwavering determination befitting the dire circumstances.
"Enhance armament!!"
Facing straight ahead, the blade of the black sword pulsed.
Immediately after, strands of darkness flowed out from all over the blade. The pitch-black torrent that seemed to suck in all light rippled, twisted, and entangled within itself. They became a spear, thick enough to wrap one's arms around, in an instant and progressively pushed forward.
Upon straining his eyes, it seemed only the sharpened tip was materialized into a solid, taking on an obsidian-like gleam. He could recall that texture. The gigantic tree Eugeo swung an axe at, day after day. The ┬½demonic tree┬╗ from which that black sword originated—the Gigas Cedar. The moment he recognized it, Eugeo understood the true form behind the full control art Kirito activated.
He had awoken the memories sleeping within the black sword through the art ritual and projected into this location the appearance it could once boast of, that of the gigantic tree that refused to be hacked down over hundreds of years. Of course, its shape and size did not remain the same as then, but its essence was exactly the same.
Tough, sharp, and an overwhelming mass. Its very existence was worthy of becoming an ultimate weapon. Eugeo's heart pounded hard. Immediately—
The huge, pitch-black spear's tip made contact with the huge spear that gathered Solus's light. The explosive shockwave intensely shook the entire grand corridor… possibly the entire Central Cathedral itself.
Perhaps even the giant tree was oppressed by the heat and intensity of the light that went beyond imagination, for it lost its momentum in charging forward. But endless darkness continued to stream out from the black sword in Kirito's hands, trying to spur the spear forward to the bitter end.
- - Sword Art Online Vol.12: Alicization Rising
Here, Kirito was facing Eugeo as he spoke, and the first line in the quoted text shows they're relatively close to each other for them to be hit at the same time by Fanatio's pillar of light. Guesstimates for the angle is to be had though, but assuming the same distance in the first part (50-75 meters) are also in between them and Fanatio now, how fast would Kirito have to turn his head to face the light beam? But since the light beam shot at the same time as Kirito turning, maybe 30 degrees would be a sufficient angle?
Fanatio was shooting trigger happy her light beams everywhere, hence why Kirito had holes on his body that were burned through and cauterized, even through some of his organs (according to Eugeo), but Eugeo was untouched despite being stationary due to being unable to move and trying to keep Fanatio in place with his ice. So really, Eugeo should at least be out of or near Kirito's field of vision when he's facing forward, else Eugeo be hit by the light beams, though I'm thinking he should be behind Kirito entirely. So yeah, low ends abound.
That is also, assuming that Kirito already had his arms raised to shoot his sword into a tentacular set of branches. Oh, and ignoring the fact that Kirito just recited two words in the span of the light beam firing, since speech is free movement no matter the speed in fiction.