I have a single eye, but I cannot see. I am often used to bring things together, but in video games, I am a weapon that lets you strike from the shadows for a silent, lethal elimination. What am I?

The market trusts my balance. The courtroom trusts it too. Each morning someone else looks down to ask if theirs is true.

In summer green, in winter bare, I line the path with quiet care. No bricks, no wood, yet I divide, What green wall stands side by side?

I'm a car part, and also a Felix the Cat villain. What am I?

I stand all alone where the blue waters meet, with nothing but waves at my sandy feet.