Complex sentence: Howard Stark states that vibranium is stronger than a third of the weight of steel, is completely vibration-absorbent, and that all the Vibranium Stark had went into making Captain America's shield.
Split into simpler sentences: Howard Stark states that vibranium is stronger than steel and weighs only a third as much. It is completely vibration-absorbent, and all the Vibranium Stark had went into making Captain America's shield.