I agree that the opalescent shade appears to be a gas lamp shade, likely off-hand made, not slumped.
I am trying to figure out why you are calling the first one "cased"??? I can't tell very well by your photo, but it appears it might have a slight iridescent finish on the outer surface of the glass and if so, it puts me in mind of "Calcite Glass", which Fredrick Carder first developed for lighting fixture globes and shades and was later used to make art glass items too.
Just a though. --- Mike