Added. Even for Exosphere, the result is crazy. Just sending the same text with additions
For every possiblty, will use 1 second (low end) 13 miliseconds (mid end) and 1 miliseconds (high end) and 0,000000003336 seconds (EXTREME END)
[0.000000003336 is speed of light perception speed, which is Flashy Flash's reaction time.]
LOW End
Assuming it comes from where Void aims, which is sky.
MID End
Assuming it comes from edge of universe
HIGH End
Assuming the universe is infinite
1- LOW-Low END:
It's both from sky and happens in 1 second
Even though taking it as low as its from sky, i'll take it as the highest layer of sky, Exosphere, which has the top height of 3000km
For the Low end, assuming it happens in 1 second (which is literally impossible since Sonic and FF can't dodge it)- 3,000,000 meters per second (Hypersonic)
LOW-Mid end
Taking the same 3000km distance but 13 miliseconds-
3,000,000÷0,013=230,769,230.76923 meters per second(Relativistic+)
LOW-High end
Taking the same 3000km distance but 1 milisecond-
3,000,000÷0,001=3,000,000,000 meters per second (FTL+)
LOW-EXTREME end
Taking 3000km distance but 0.000000003336 seconds-
3,000,000÷0.000000003336=8,99280575539e+14 meters per second (MFTL+, 2,999,677.1150894 times SoL)
MID-Low end
Assuming its from the edge of universe (46.5 billion light-years: distance between earth and the edge of universe), in 1 second-
46.5 billion light years into meters=4.39923966975e+26 meters per second (MFTL+, 1.467.428.399.999.975.936[1,46 quintillion] times of SoL)
MID-Mid end
Taking same distance but 0,013 seconds-
4.39923966975e+26÷0,013=3.38402974596e+28 meters per second (MFTL+, 112.879.082.033.477.976.000 [112,87 quintillion] times of SoL)
MID-High end
Same distance but 0,001 seconds-
4.39923966975e+26÷0,001=4.39923966975e+29 meters per second (MFTL+, 1.467.428.399.999.975.950.000 [1,46 Sextillion] times of SoL)
MID-EXTREME end
Same distance but 0.000000003336 seconds-
4.39923966975e+26÷0.000000003336=1.3187169273831e+35 (MFTL+, 1,318,716,927,383,100,000,000,000,000,000 × 10⁵ [1.31 Nonillion times 1.000.000 {According to
https://www.calculatorsoup dot com/calculators/math/scientific-notation-converter.php is "out of real number}] times SoL)
HIGH ENDS
{Of course using of time is useless here, so i'll just use assumes}
HIGH end 1-
The universe is infinite and whatever the time it takes for blade to hit is irrevelant, speed of attack is Infinity Speed
HIGH end 2-
The attack is beyond the causalty of the universe, because it is from Hyperspace which is out of causalty. Hyperspace is not just exceeding distance, energy and size but also time and other rules of universe since it is outside of causalty, and must have a time of its own. Moving in its own time and moving above the time flow of universe, the attack would be Immeasurable Speed.