In order to make the Blue Mage sorc viable in Hell, you might want to limit mastery rather than outright ban it. I'd venture to guess that Diablo could be considered a master of fire and/or lightning.
Otherwise your sorc might be ok for fire (depending on skill selection) but pretty weak in lightning, as the reason CB is a "near uber" skill is because of the synergy between CB and LM -- CB on its own is still the same as it was in D2, that being not too strong.
A blue mage should use blue items of course! Sapphires and frost nova items should be valued. You could go for a Plague-like set of restrictions; Plague can't use any item unless it has a poison-related attribute on it, whereas a blue mage might need a cold-related attribute. Your idea also looks a bit like the Borg variant I saw around somewhere (I think for Diablo1) where the creator drew up a chart of the item classes and what monster the Borg had to "assimilate" in order to be able to use each kind of gear.
Anyway, good luck with your variant!