What is the deffinition of "impossible?" For different worlds in different stories, "impossibility" changes. In our world, walking on water with no help from equipment and/or technology is impossible. In many stories, walking on water seems like the most natural thing in the world to some. Without any help or special powers, even. It's something that's common, something they can learn, something they're giften with, etc. etc. It's ludicrous, but depending on the story and setting it doesn't need to be ridiculous, and can even be quite cool, depending on what they do when walking on water.
Arlong's not a character that makes one laugh... he's one of the darker characters encountered in the early parts of the manga/anime (though he pales compared to some others). It's something else with Hachi. He looks funny and he acts funny. Arlong's design is supposed to look intimidating, and he actually uses the nose as a weapon. But I suppose this is all about how one views it. I first watched One Piece as a young teen, and although now an adult I still like to look at it the same way because I find that the most entertaining for me. Sure, I can be a bit more sceptical to some elements, but it's all part of what I mentioned before, which is going with the story. If the story says it works that way, then unless it really contradicts something previously stated, it simply works that way. Dragons in tons of stories breathe fire. How? Who knows. They just do. Could be magic, could be something special with their lungs or something else. That's just how it works. But once again it's about personal differences between the two of us. It can't be helped that we're different. Everyone is different and like different things.
I don't have anything published yet, and as a greenhorn I'm glad for any advice I get. But what you're telling me is that my story won't work because it won't follow the laws of physics normal human abilities. But those are your thoughts. You don't like it, and I'm fine with that. You don't have to read it. Even if you do, I will not change what is essential to the story. It's a different world, the laws of physics don't work the same there as in the real world (for reasons that are explained in the story), and where there are people with superhuman abilities and special fighting styles and techniques.
As for pacing a fight scene, I know from experience that it's hard. I have no doubt many, if not all, of my fight scenes need more editing to make them perfect. When I write out the first draft I write on instinct and what I think sounds good at the moment. But editing exists to let writers get a second thought on whether they think the story is good or not and change it should they wish. I'm not a perfect writer. Neither are you, neither is Dorian, neither were C.S. Lewis, J.R.R. Tolkien or anyone else! We're just human, and we have to live with imperfection. What you find perfect in writing might be something someone else finds unsatisfying or downright bad. The arguement me and you have had thus far merely proves it. We like different things and have such different views. But we both like what we like for our own reasons.