that if you go up and kill all the archers, you can stand where they were and take pot shots with a ranged weapon, or in my case soul arrow. Time it so just as he moves his shield aside you hit R1, and as soon as you launch your attack step back. He'll launch his, but it will hit the wall and you'll score your attack. Maybe mine glitched, but I was 100% safe just standing there waiting. His blue glowing javalen looking attack just hit the wall, and I was safe. For me it was just a battle of attrition and waiting for my friggin MP to regen
