For me, it's mostly sleep and the winds of magic that dictate my speech. But I could sleep amazingly and wake up with incompetent speech. It's probably too close for you to start experimenting like this, but a mild testosterone boost with something like tongkat Ali may give you jump for a few days (if that helps). Down a darker path, there's that drug people use for public speeches that makes them have zero anxiety, starts with a P but I forget the name. Of course, if you're using a substance to save your speech, you're headed down a high likelihood of addiction path.