I used them for a sparring session on Saturday night this past weekend, and used them to my full fighting speed and swung them how hard I normally swing. The swords were fine and held up, and the sparring partner is still alive. They didn't get skewered by the tip. They didn't get a cracked skull from the lack of a waylay tip. They didn't explode.
They are so soft and weigh absolutely nothing that it is almost impossible to hurt someone with them, unless lighting strikes you and the person you're fighting mid combat. That's the only way I see anyone getting hurt with them.