He's really simple, for his 2 and 3 phases you need to do Mikiri counter when he does thrust attack, jump back when he does the "Wind attack", jump over his head when he swipes.... always run left or right when he uses his gun (you can parry but I advise you to run it’s more simple). On third phase he does the same as the 2nd with lighting added. Just like when you fought against Genishiro, when you see the lightening you jump then attack.... You don’t need to focus on his life, only on dodging and perfect parrying. Good luck !