How is a banana leaf a symbol in this book?

This banana leaf fan is a symbol of hate. As Weilong is talking to her aunt, Liang looks at Weilong’s face through the fan. Liang shreds the fan as Weilong is speaking. Weilong finally comes to the conclusion that her aunt is imagining shredding her face. Even this show of hate does not discourage Weilong from her mission.