As far as I know, belief does not grant power. It does however allow a supernatural being to act more freely in the mortal realm, which technically does indeed improve one's power level in a sense.
From Backup, mortal
knowledge is needed for Nevernever entities to access the mortal world. (But not
belief; knowledge of an entity as a myth is sufficient. Apparently even pure fiction, if you believe Bob's comment about the D&D cartoon helping out Tiamat.)
There's a WOJ about 'the beings themselves don't change' which I think means that they don't lose power in the Nevernever, they just can't access the mortal world. (And presumably they can be forgotten in some universes, and remembered in others.)
This is important because technically Ethniu should not be able to act so rampantly in the mortal plain.
Yes, this is a very good point.
Some possibilities:
- Maybe this
is her "limited" power level. If both Mab and Ethniu are equally limited, then if Ethniu's stronger to start with, she'd still be stronger than Mab.
-Maybe the rules are changing as things move toward the BAT, some sort of super-Conjunction, possibly related to the 666-year "starborn cycle".
-Maybe Nemesis... but I really doubt it can infect beings on this power-level.
- As you suggest, maybe Ethniu is just a different sort of being, a titan/proto-god, and thus the rules are different for her.