Come on, it is a novelty. Thinking of it otherwise isn't being honest with yourself. Think about it, how many soldiers carry one? I wouldn't have, I wouldn't even draw my rifle bayonet from the arms room. Bayonets are obsolete, and they really went out with autoloaders.
If you really want to see how ridiculous it is, and it is ridiculous, you just might not know it yet, go and find a bayonet course to run with one. I guarantee you something will break. The pistol, the bayonet, your hand, but something ain't coming out the other end in one piece. Not to mention how much more dangerous it would be to run a course with one than a rifle. Too easy to hurt yourself.
How do I know? Been there done that, broke some rifles and bayonets in the process. But to hang on the wall? To use in a movie? Go for it. Just don't think it is good defensive idea or show up at a range with it on there if you want to be taken seriously by your peers.