Complex sentence: The Qin variant of seal script became the standard and was adopted as the formal script for all of China in the Qin dynasty, and was still widely used for decorative engraving and seals (name chops, or signets) in the Han dynasty.
Split into simpler sentences: The Qin variant of seal script eventually became the standard, and was adopted as the formal script for all of China during the Qin dynasty. It was still widely used for decorative engraving and seals (name chops, or signets) in the Han dynasty.