Answer:
I hide in a dark tunnel awaiting my time. I can only be released by pulling back. Once released I may do unstoppable damage.
My first half means container. Not a lot of people understand my language.
I can be thin but not fat; in your body but never on your placemat. I'm always better when I'm fresh but you'll never see me in the flesh.
A dagger thrust at my own heart dictates the way I'm swayed. Left I stand and right I yield to the twisting of the blade. What am I?
I am put on the table, cut, but never eaten. What am I?
you hold my tail while I fish for you