Riddle #1816

Question: Looking at my face, I'm no more than six.
Look at the rest of me and I'm 21.
You'll see my twin and me in Las Vegas.
Say my name and you'd be uttering a threat.

What am I?

Question: What tastes better than it smells?

Question: What goes in the water black and comes out red?

Question: What asks but never answers?

Question: I have 6 faces and 21 eyes, but can't see a thing. What am I?

Question: What cannot be seen or felt, but can only be broken by voice?