Issues with Mesh Decals

Hi Im going for the sort of edge decal detailing that we see in Hitman etc. Namely, a open right-angled mesh with a normal map ( maybe colour etc) that “masks” the hard edge of the low geometrys hard edges and fakes-in a bevel based on the normal.

There are a few issues im getting- Darkness. The material appears unduly dark in the viewport (settings for material in shots below). There is also the roughness, that, despite being set up the same as the underlying object, does not seem to work.

The last thing would be the strange sheen on the alpha filtering…

Its been a bit of a mare, and while I can find tutorials on some edge decal stuff I cannot find one that details this application.

If anyone can help I am sure it would be of benefit to a lot of folks. Searching issues of this sort took me to lots of forum posts with mesh decal issues, but sadly no replies. Epics own documentation on this precise usage/method, despite it being so popular in games, does not seem to exist…

Anyway, to the shots. Thanks
(ps, I have the decal setting enabled in the editor prefs too)