OK, I have absolutely no idea how to do this at this point. I probably need something that packs a bit more punch so that I can do actual damage during those limited seconds when I'm not dodging or chugging Estus (so much unavoidable damage in this fight, insane
).
One-handed R1s: Claymore +6 does 135, Red Fire Halberd +5 does 118 while the Irithyll Straight Sword +3 does 105 per hit. The latter works out for the best DPS, probably, but there are such limited attack windows that it's simply not enough. None of my other weapons seem any better suited for the task, though. I don't have the strength for the really big weapons.
I don't want to summon for this boss fight as well and now I'm really considering quitting. If that's the norm from now on, that I cannot beat any boss alone then I see no point in continuing.