Agreed, making it rare doesn't make it not OP. Obviously what we need are some new Fire and Darkness spells that make sense for wands and aren't already on sticks.
I suppose I could change the Fire wand over to Cremation (OP edited to reflect that change) and it will totally make Phoenix/FireWand/FireBolt decks all the rage. That might not be that bad. But Darkness really does need a new spell.
Edit: Also, after considering what Demagog pointed about above, and noting that Retrovirus is both upgraded and requires a sacrifice to use, I've changed the Death wand to Plague as well.
I'm not particularly happy about the fact that both the upgraded Entropy and Light wands provide very similar creature buffs now, but it's better than the unupgraded Light and Life wands providing very similar healing spells, so I guess it stays.