This retexture was made to solve the problem. The textures are darker than vanilla ones, so light beams become soft and pale and look much better with ENB.
UPDATE: Added optional textures for vanilla dungeon mist clouds (made by request).
NOTE: This mod isn't for vanilla Oblivion setup. Light beams and dungeon mist with this retexture will be almost invisible in vanilla game without ENB.
INSTALLATION:
Unpack the archive and drop Textures folder to your Oblivion/Data. Merge folders and overwrite files if needed.
Use Archive Invalidation function of OBMM.