WHEN and WHERE did old Dante meet march 10 speed?
An example on the top of my head is when he effortlessly dodged a gun shot by Nero on the humanoid Sparda lookalike statue.
First, look at the distance seperating them at 4:00. You can notice that it is a fairly short distance. Now look at 4:17 to 4:22.
An another instance is during the short skirmish between Dante and one of Sparda's fodder disciple.
Pay close attention to the lightning at 2:38 to 2:42. Notice how the two of them were fast enough to strike at each other at the exact time of when the lightning began and before it faded away. Lightning bolt travels approximately at 224,000 mph -- or about 3,700 miles per second.
The next video could also be considered as reaction time.
At 0:45 to 0:49 Dante shows the capacity to open his mouth fast enough to grasp a bullet shot with his teeth.
This video is one of my favorite.
Dante, at 0:05, dodge another bullet by flinching his head to the right without even looking. He also counter every gun shot at close range from Lady with relative ease.
I presume there are other feats I could show you, but I feel to lazy to make additional research. Anyway, I believe Dante in base form is at least at Mach 5. When it comes to Mach 10, I was thinking about his Devil Trigger.