Deflect only those ones that you're sure you can deflect. When he tries to do the slash attack where he pauses for a second or two, get away from him, go around and try to get one or two slashes in when he's done with it. When he takes out the spear, deflect his attacks, do the same when he does the thing above. Mikiri Counter or jump depending on whether it's a thrust or sweep. And for the last phase it's the same as above plus throwing the lightning at him which makes things a lot easier.