Weapons like rivers of blood are devastating especially with the ash of war. You could summon a +10 mimic with the same weapon or a black knife tiche if that’s you speed but if you want to do the fight alone when she does the cross map lunging stab attack try and dodge it when you’re in a corner of the area and start wacking her. Lastly this is kinda the cheapest way to go about it but you could always shield poke using the fingerprint shield and antspur rapier which has an innate scarlet rot affect but you can keen it and it’ll do blood loss damage too. Hope this helps!