Notes from author
A Witch of Sin, using Velka's Rapier and an enchanted Composite Bow with Moonlight Arrows.
Black Cleric Set for lore and style, Wolf Ring for Poise, Bellowing and Crown of Dusk for spells.
Until you get the rapier in the Painted World, you can also go with a magic Uchigatana. Velka's Rapier requires Twinkling Titanites, so you don't have to farm too much.
The spells don't matter, but getting 6 attunement slots is recommended.
Instead of Logan's Catalyst you could also use the Tin Crystal Catalization Catalyst and the Silver Knight Shield could be replaced with the Grass Crest Shield (or just use Green Blossom before boss fights if you need to).
Only tested in PVE, but I'd say it's also a good build for PVP.
Let me know if you like the Witch of Sin and feel free to experiment with the build!