I just want to know two things: 1. Why would Henry even need the Hammer to destroy Mushu’s heart? 2. Umm, couldn’t Henry just speak into Mushu’s heart, to make him stop attack? Yeah, I know. My questions are pointless.
To address your second question, have we ever seen a non-magic user command someone to do something using their heart before? I’m guessing not just anyone could pick it up and make the dragon do something? I know Henry is the author, but his “power” seems to involve use of the quill/pen.