Usually blunt metal blades (not live blades) are used in demonstrations to impress the public. But even then, they are very dangerous. We have had a few accidents even with wooden tantos.
Sometimes we do practice tachidori with real sword (blunt) but it is under controlled environment, not grading tests where people might become too excited. I know I cannot refuse if sensei asks me to demonstrate with him using a metal weapon, but for sure I will be scared to death. I will definitely refuse to do my grading with a metal weapon.
|