If someone were to point out that his sword was real, the fight would end and he'd be both disqualified from the bout and punished. Since no one else was going to step in since they knew Clavis would win then she was going to. I'm guessing she was gonna loudly get their attention and tell them to stop, but as she was getting close enough for the two of them to hear her properly his sword got knocked out of his hands. It was simply bad timing.