Modular LED lighting devices and systems with oblique edge diffusion panel

A lighting system having at least one lighting device module, each lighting device module comprising:

• a light diffusion panel having a primary light emitting surface and at least one side edge defining a plane at an oblique angle relative to the primary light emitting surface;
• a plurality of light emitting diodes (LEDs) arranged to emit light into the light diffusion panel, for emitting light from the light emitting surface of the light diffusion panel;
• one or more threaded fasteners extending through a portion of the housing and through the light diffusion panel;
• and
• a housing on a surface of the light diffusion panel opposite of the primary light emitting surface, and a bracket assembly connected to the housing for mounting the housing to a mounting surface;
• and
• a cover panel arranged to cover a portion of, but not the entire primary light emitting surface of the light diffusion panel, the cover having one or more threaded openings for receiving the one or more threaded fasteners, to couple the housing, the light diffusion panel and the cover panel together;
• wherein the cover panel includes one or more projections corresponding in number to the one or more threaded openings, wherein each respective threaded opening is in a respective one of the projections.