Since Thundarr was on a network (unlike, for example, He-Man), he couldn’t have an actual bladed weapon. So he got the fabulous Sun Sword, which even little kiddies knew was a light saber knock-off. Still, it’s always good to have a signature weapon. Not that he was ever allowed to kill anything with it. Robots, always robots.
This is a pretty rudimentary monster, but one of the charms of the show, aside from featuring both magic and super-science, is that you always got lizardmen and ratmen or some kind of beastie each week.