When I render this axe on top of everything (by duplicating the camera, making that duplicate a child of the original camera, setting its culling mask and volume layer mask to the viewmodel layer) It makes the axe fully white. Adding the default layer to the volume layer mask produces what you see in the second image, the axe rendered correctly, but I have this massive fog thing. How can I fix this?
Shouldn’t use multiple cameras in HDRP unless you enjoy pain.
Instead, do a custom pass.