Answer:
Up on high I wave away but not a word can I say.
It's usually found dried, but often kept slicker. Above another need, it's said to be thicker. What is it?
I open wide and tight I shut, Sharp am I and paper-cut fingers too, so do take care, I'm good and bad, so best beware.
I am a fire's best friend. When fat, my body fills with wind. When pushed to thin, through my nose I blow. Then you can watch the embers glow.
Many hear me, but no one sees me, and I only speak when spoken to
Almost everyone needs it, asks for it, gives it. But almost nobody takes it.
Difficult
Animal
Easy
Food
Funny
Kids
Logic
What am I?