Dark Cloud Demon Shaft Boss - Black Knight
Much like the Dark Genie this boss has two phases, the first one is a total pain in the rear but luckily it gets much easier for the second phase. I recommend you just use Xiao for the entire fight. Honestly that character is the best character to cheese all fights.
The first phase is pretty easy, he has two attacks that are worth mentioning. The first attack a bluish aura surrounds his body and he charges at you. You can easily avoid this if you break target on him or if you're far enough away you can keep him targeted while avoiding it. The second attack he does is he throws a spinning like blade at you. You can easily avoid this too as long as you are a decent distance away.
I used Xiao and only had to heal twice during the first phase
He dismounts and this phase is honestly even easier than the first. What I did is I used Xiao and held down the left stick to constantly back up while also spamming X to attack. I literally was able to avoid every single one of his attacks while hitting him with usually 3 out of 7 shots. He went down extremely fast, so this phase he only has about 1/4 the health as the phase before.
Your reward is the best sword for Toan, Chronicle II.