Captain Nazi got punked by freaking Catman.
Come on. Catman was written as a way more interesting and formidable character for Villains United and Secret Six than in previous appearances. He even went toe-to-toe with Batman. It could be argued that the reason Catman was able to beat him was because Captain Nazi underestimated him. Captain Nazi has gone toe to toe with Captain Marvel and lead the Fourth Reich to victory against the JSA. He's far from weak, but you bring up a good point. Captain Nazi was defeated by Catman, who has no powers. That means even though it appears that Captain Nazi outclasses the Black Terror a bit, he has weaknesses that can be exploited, like his eyes and his arrogance.