So if 294 u/s is the default movement speed and 400 u/s is the max, why even bother telling the player in such a complicated way?
Just change the tooltips of the buff and the tooltip of the rune to make it clear that the Buff increases your movement speed to the maximum (outside combat) and the rune is just helpful inside combats.
It's still a scam like letting you use ferrari on a roadway but you can't drive faster then 30 mp/h. You literally need to give warnings on coffee that it may be hot if you don't want to be sued.
Guess online fantasy worlds do not guarantee
buyer protection service
¯\_(ツ)_/¯