I'm sure that for LARP they are probably fine. I've handled very similar types of latex sword boffers, and they are nearly completely useless for historical swordsmanship. They are way too light, they don't behave realistically when the blades come together, and they don't "move" right when in motion. I assume they are made for LARP, where no protection is worn, and a hit point based system is used, in which case you would want something to be very light and very safe.
