Blazblue's main character vs. RWBY's main character.
Ragna's at his Chrono Phantasma levels and Ruby is at Season 3 levels. Ragna's not allowed to use the Idea Engine or activate Blazblue, and Ruby's not allowed to use her eye power (mostly because we have no idea how that works).
If either one of them is capable of blitzing the other, then speed will be equalized.