This is an art-directable cloth shader imitating the appearance of cloth/silk using a customized Fresnel effect. The general reflectivity and properties of cloth can be achieved by just using the material editor without actually changing the lighting model that Unreal Engine 4 uses.
The overall nodes
The dot product measures the angel between player's eyes looking at it and the actual surface angel (the pixel normal can be changed to the textured normal from the material normal map)
1-x node controls whether the edge is brightened or darkened; power node controls tthe contrast level, multipy node controls the brighness of the edge
The texture coordinate controls how condense the texture looks like
Resource from Uncharted 2: Character Lighting and Shading by John Hable