Having had one of these failures in a Canadian 212 main blade (blakmax knows the story) I agree with everything he says.
The TSB Class 3 (means fairly serious) investigation agreed that the blade had delaminated, but were unable to determine exactly why.
I can report that after ~22K in the biz I have never been that !!!!-scared in my life - and I've had my share of engine/component/systems failures.
