Answer:
I have an eye, but I can't see. I usually have to work with something in my eye. What am I?
I am a protector. I sit on a bridge. One person can see right through me while others wonder what I hide.
I can go through glass without breaking it.
You can read me both ways I wear; One way it's a number reversed a snare.
Born of sorrow, grows with age, you need a lot to be a sage. What is it?
Though not a plant, has leaves. Though not a beast, has spine. Though many wouldn't need this thing, It's more valuable than wine.