Haligtree is optional and higher level than Farum. You can do Haligtree anytime where as Farum will move the story forward and lock out certain parts of the game
Phase 2 is easier if you ride around behind him and wack on his foot. He'll roll away instead of attacking, rinse repeat. Just have to juke a little bit away if he can get in a swing before you get back behind him.
After experiencing almost all that Elden Ring has to offer, my new passion is watching the endless compilations of rage/fail videos. Many a controller, keyboard and mouse have died to bring us such entertainment.