So about SM and Necrosis spell and Blood-Caked Blade, this is how SM procs" Soul Fragments can be gained from any auto attack, including off hand swings. They can also be gained from any ability that simulates a weapon swing, regardless of whether or not it deals damage" icy touch is not a weapon swing even tho it does apply as melee class ability. blood caked is an extra auto attack that does weapon damage. As for Necrosis, take example Scourge strike, it has 2shard proc because it does shadow damage and physical damage in 1 swing, Necrosis simulates the same thing from auto attacks. So in the end, Icy Touch doesn't proc shard but Necrosis and BCB does.
P.S Also just to mention things like " I heard, friend of my friend told maybe it's like this or that" won't really work, having solid evidence to back up your statement or source would be much appreciated.