In ancient China, several powerful weapons were renowned for their effectiveness and impact on the battlefield. Determining the "most powerful" weapon is subjective and can depend on various factors, such as the specific time period, context, and personal perspectives. However, here are a few weapons that were highly esteemed for their power and influence in ancient China:

1. Composite Bow: The composite bow, often made with layers of horn, wood, and sinew, was a significant weapon in ancient China. It had a long range, high accuracy, and could penetrate armor. Skilled archers could rain down devastating volleys of arrows upon enemies, making the composite bow a formidable weapon on the battlefield.
2. Crossbow: The crossbow was a revolutionary weapon in ancient China. It required less training and physical strength compared to a traditional bow and arrow. Crossbows had tremendous penetrating power and were capable of launching bolts with significant force, often with deadly accuracy. They played a pivotal role in various military campaigns and siege warfare.
3. Dao (Chinese Broadsword): The Chinese broadsword, known as the Dao, was a versatile and effective weapon. It had a curved single-edged blade and was designed for close-quarters combat. The Dao could deliver powerful strikes, cleave through armor, and had a wide cutting surface. Skilled practitioners of the Dao were renowned for their ability to execute devastating slashing techniques.
4. Halberd (Ge): The halberd, also known as the Ge, was a polearm with a large blade attached to a long shaft. It combined the cutting power of an axe with the thrusting capability of a spear. The halberd's versatility made it effective against both infantry and cavalry, allowing for slashing, thrusting, and hooking maneuvers.
5. Chariot: While not a handheld weapon, chariots were crucial in ancient Chinese warfare. These two-wheeled vehicles, pulled by horses and often armed with blades or scythes, allowed for swift and devastating charges. Chariots played a significant role in ancient Chinese battles, particularly during the Shang and Zhou dynasties.

It's important to note that the effectiveness of a weapon depended not only on its design but also on the skill, tactics, and strategy of the warriors who wielded them. Additionally, advancements in military technology and tactics throughout ancient Chinese history influenced the weapons' effectiveness and prominence on the battlefield.