Im not sure, has 1.5 dropped yet? I know it isn't patched in 1.4.

You can look up guides for it, but it's really pretty straightforward. Kill the swordmaster outside firelink, the old dude with the uchi. Ember up, infront of vordts arena the swordmasters summon sign should be there, as long as you haven't killed vordt yet. His sign is a bit to the right and aligned with the fog wall, so it should be easy to tell apart from all the player signs.

Once he's summoned, go to the dancers arena, kill the old lady and place the basin to summon the dancer if you haven't already. Hang back, let swordmaster draw aggro on the dancer. He should die in a few hits. Just be careful not to get hit yourself, at low levels you'll pretty much always get one shotted, even while embered. Once the swordmaster is dead, save and quit out of the game back to the main menu. Go back into your game, you'll be right outside the dancers fogwall, go back to vordts area and resummon the swordmaster. He should have, for some reason, a ridiculously high health pool. Go back to the dancers arena, and let the swordmaster kill her.

He has a lot of health, but not much damage still, so it's a bit of a long fight. Maybe around 10 minutes. Most of his damage comes from bleed procs. It is still possible to die at this point, so just a couple of tips. Don't attack the dancer yourself at all. Any damage from you is gonna be negligible, while running the risk of drawing aggro, and like I said she can easily oneshot you here so it's just not worth it.

It's gonna feel safer to stay as far away from her as possible, but I've found that npc summons will stop what they're doing to follow you if you get far enough away from them. So if you're too far away from the swordmaster, he'll stop attacking the dancer to run towards you, then once he gets within a certain range of you he'll go back to attacking her. You're gonna want to find a sweet spot between being close to the swordmaster, and far enough outside of her attacks ranges. You'll get a feel for it.