The butcher has 3 attack patterns:
1. He swings his weapon around and follows you.
2. After that he shoots fireballs and swings his weapon again.
3. After swinging his weapon again, he throws his weapons at you.
2 and 3 repeat, with 1 in between.
My strategy is: Attack him until he starts swinging. Jump over him and attack him until he starts swinging his weapon again. The fireballs do only 1 damage and the thrown weapons most likely won't hit you.