What do you get when you dress the Hulk in Captain America's clothes? A Star-Spangled Banner.

If Captain America's Shield Is Made Out Out Adamantium, What's Hawkeye's Shield Made Out Of? Quicksilver

I think comic book bad guys have the right idea, aiming their weapons directly at Captain America's shield. That's probably his weak point.

If Captain America's shield is vibranium, then... Hawkeye's shield is Quicksilver