As long as you don't have any independence, then you are stuck doing what your parents tell you to do. You turn 18 soon. 3 years is a very short amount of time. It may seem like a long time to you now, but that's because you have only been alive for 15 years and you weren't really making any memories for the first 5 of them.
Do you earn your own money? Your money, your choice. Get a job and you can buy the things you want, local laws permitting. If the law allows you to buy the knife but your dad still says "no", then you're kinda screwed. "My roof my rules" is pretty iron clad, and unfortunately you do need to be 18 before you can rent a storage unit where you can keep your own stuff.
One thing you can do is try meeting your dad halfway. Earn the money yourself, buy the knife (if the law allows it) and give it to your dad for safekeeping. Have him hold on to it for you and then ask him for it when you want to use it. This will give him some discretion and allow him to fulfill what he may believe are his duties as your father by keeping you from doing something stupid. After all, most of us older adults can remember how stupid we were when we were young.
Don't baton with it. If you must practice batoning with a folding knife, then disengage the lock first and fold the knife halfway closed to roughly 90 degrees with the handle so that the knife is perpendicular with the wood that you're trying to split, while the handle is parallel with the wood. This way you can't cause the folding mechanism to get damaged so easily.
I don't recommend batoning in the first place because people can get rather stupid with it. A knife is not an axe. It's only for splitting small pieces. There are better and smarter ways to split wood without bashing your knife through it and risking breaking the blade.