Does anyone know what Epos's feather does?

Tom gets a feather from Epos and adds it to his shield. But the book never says what special powers the feather gives the shield. When we tried to গুগুল it, we discovered that other kids are পাঠ করা different versions. Some beasts are named differently and the special item they get from each beast is sometimes different. Also, what that special item does is slightly different. We are পাঠ করা the Scholastic version bought in the U.S. Does anyone know what Epos's feather does? Thanks.