Answer:
I have a straight back and sharp teeth to cut objects.
In wealth I abound; in water I stand; as a fencer I'm valued all over the land; at Venice I'm famous; by farmers I'm prized; respected by law yet huntsmen despised; consternation and ruin ensue when I break; And the beasts of the forest advantage won't take.
Angels and pilots work with me.
What is black and white and red all over?
I am always in front of you but you will never see me
I am always hungry, I must always be fed. The finger I lick will soon turn red. What am I?