Hubs with a 5mm on each endcap work one of a few ways:
- Each end of the axle has a larger Allen fitting hiding below the endcap that's used to get the opposite side off. This is pretty
- Wrench english is required to gain control over which one breaks
free. It's unfortunate this exists but it does. There are some hubs
where one end but not both have a hidden fitting, as above.
There are also some hubs where after removing one, the other, or sometimes either endcap, the whole rest of the axle assembly can slide or get bonked through. In some cases in wrench English designs, this afford the ability to grip the axle to get the other endcap loose.
I believe the shouldering configuration on a Vision 35 axle is such that with the right endcap removed, the freehub body will slide off the right side and the axle will slide out the left. I don't recall whether there are wrench flats in the end of the right side of the axle but if there aren't and if the wrench english approach doesn't work, another plan could be gripping the axle somewhere that cosmetic markings won't make any difference such as as the center with a close-fitting circumferential clamp or pedal/axle vise of a soft material, i.e. Park AV-5 or a damper service tool that happened to be the right size.