All of these frames captured the event from the gun getting fired to Izana saving Kakucho.
I set the frames at 24fps since anime typically run in that.
I overlaid 2:21 with 2:22 to find the distance covered by Izana in a single frame.
Izana moved 0.69m in a single frame.
To find out how much distance izana moved offscreen after the gun was fired, we have to multiply 0.69m with how much frames it took for izana to appear after the gun was shot.
The gun was fired at 2:16, and then Izana appeared on screen at 2:21.
That means it took Izana 5 frames to appear on screen after the gun got fired.
0.69×5= 3.45m offscreen
3.45m offscreen+ 0.69m onscreen = 4.14m total distance ran by Izana.
Now, as for the arm movement.
In the last second frame (right before they switched to kisaki's screen), Izana is shown to fully extend his arm backwards, meaning he'd need to at least move his arm 90 degrees.
You might argue it's contradictory to the manga but in the manga, Izana's arm was still in motion, meaning the movement still isn't completed.
Full movement:
4.14+ [(0.699π)/2]= 5.238m.
Speed: 5.238 × 381 / 0.45= 4434.84m/s.
Hypersonic+.