I have included 2 options to modify the appearance of a wall reveal below:
1. VG > Walls > Projection/Surface
Typically the reveal is included in the V/G > Walls > Projection/Surface setting. You should be able to toggle the lineweight as needed here. Or you could do on an element basis, by right-clicking element > Override Graphics in View > By Element > Projection Lines:
Video Example: http://screencast.com/t/NjhlNjc5
2. Linework Tool
Reveals can be overridden with the linework tool as other element types:
Video Example: http://screencast.com/t/YmM2YTM1MWIt
The Linework tool is an option if you only have one (or few) reveals but not with many considering all the views and changes that may be affected. The element basis for an override does not work with reveals (but does for wall sweeps) and the Override Graphics in view for projection lines on walls affects the entire wall, not just the reveal so it is not an option either. I suppose the only answer is a hybrid combination of the above functions until Autodesk realizes they only need to add a similar category in the view visibility controls, like the Wall Sweep category.
So this has seriously NOT been fixed at all yet? My reveals as added objects of the wall family causes so much more work. They look great for renderings, show up in sections, but in elevation I have a big blob of a line with embeded 2" reveals.
This has been on the wishlist for a while also. Please keep us posted on when this will be fixed.