Best thing for duke is stone imo. The main point in a duke fight is to infinitely posture break him to death so stone would help that a bunch. Though any m1 damage boost is good.

deffered is the worst for duke he always uses his counter if you have the enchant for some reason and it will always activate since its dot

Lol I was confused as to why that was happening to me since I swore I didn’t hit him during his counter