These exotics aren't mean to be a shaman's go-to weapons, so it's worth making that clear up front.

Both give the shaman something fairly attractive, though.

The stone provides a weapon that can lag. Not amazing lagging potential, but it's something shaman otherwise struggle with.

And the sphere is a light, unbreakable weapon that can prog stacking vulnerability to negative (hi demonfire).

Both exotics prog on average 1d8 rounds.

Like frostblade and abilities like it, they're meant to provide some utility in situations where that utility is needed or when better options aren't available.