with a heavy hand
1. In an excessive, authoritarian, or oppressive way or manner. The police dispersed the protesters with a heavy hand. My father always punished us with a heavy hand.
2. In a clumsy or uncoordinated way. People who aren't trained in this discipline often use the tools with a heavy hand.
heavy hand, with a
1. In a clumsy manner, as in You can't use that delicate equipment with a heavy hand. [Mid-1600s]
2. Overbearingly or severely, as in Children brought up with a heavy hand often rebel in later years. [Late 1800s]