You're being an annoying fanboy. I don't think a single person on the thread has agreed with you thus far and you keep ranting on and on. Let me list the facts:
Zabuza has the weakest sword while Mangetsu has mastered all seven including his, six of which are far stronger than the Kubikiribocho. We don't know most of what Mangetsu has to offer, but its safe to say that he can use the Hydrification Technique and the Hozuki Water Gun Technique. I see a lot of people saying that by using the Hydrification Technique, Mangetsu is immune to just about everything Zabuza has to offer which is true, but Mangetsu is not going to sit there as a puddle and wait to get hit, he's obviously going to fight unless he is forced to turn into water to survive. We've seen just about everything Zabuza has to offer though. His Suiton prowess is nearly unmatched in the manga and you said that he is only susceptible to fuuton. Mangetsu on the other hand has been said to be susceptible to strong katon and raiton. So now, lets get this straight, Suigetsu can survive a point blank TBB from the second strongest tailed beast, and he still doesn't measure up to Mangetsu. I would say that very strong TBB>>>>>>>>>>>>> a strong katon anyday, making Mangetsu most likely immune to katon. And you're forgetting the fact that the things that apply to Mangetsu will apply to Zabuza too. That raiton you were talking about would kill Zabuza. When Zabuza goes head to head with a raiton user that can stream his or her chakra, his sword will get chopped up and he's screwed. He also has no counter toward raiton techniques. Mangetsu is also pretty much immune to suuton attacks considering he can turn into water. On the other hand, Zabuza got taken out by a suuton from Kakashi in their first fight. Out-debate that, fanboy