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The fan section of a turbine aircraft engine contains fan blade separators known as annulus fillers, or simply as spacers. The material specification of an annulus filler is usually 7075 T56 aluminum alloy with a painted coating. The highlighted area in the drawing at left represents the annulus filler component, of which there are 22 in this engine. Annulus fillers are attached to an outer rim (rotor disc) by means of insertion."

Apparently, they simply keep the fan blade tips evenly spaced.

The lighter areas in the picture between the fan blades are the annulus fillers. Emirates have had an annulus filler let go before, ex GLA diverted to LHR for an engine change. The bright green bit in the image above is part of the nose cowl structure that the acoustic panels 'nail' to.
Now another pure guess here but possibly a failure of the inner barrel acoustic panels due to fatigue causing a heavy surge (reverse compressor stall flow) and subsequent failure of the outer skin. That would also account for minor damage to the blades.