Don't jump the knife with your arm, use your wrist. At the same time, once for the left hand and twice for the right hand.
And try to use Tongnan Dao. Don't take a dime. Because the iron knife is heavy. It is easy to practice.
Horseshoe knife? (mǎ？ tí？ dāo)
A semicircular knife shaped like a horseshoe.
The fourth episode of Jin Ping Mei Hua Ci: Yun Jun said, "You cut vegetables in the bucket with a horseshoe knife, and it didn't leak at all, and it didn't land at all."