Damn, making me feel small. I spent hours on that, we'll a good chunk of it being passive attempts but still, many deaths. Many tries.
I honestly felt like it was going to take me forever. I was getting good enough to get to the second form relatively unscathed, but just couldn't get any kind of groove for the second form. Then it just clicked and I mikiri'd the shit out of him every time he did his jump thrust (which was quite often) and otherwise kept enough distance between us to make the lightning less of an issue.