I think Dual Sellsword is what I ended up with later on in Souls 3. One of those "how is it this good" noob/early weapons, like the Bandit Curved Sword (can't remember what it was called, the rusty-looking curved swords with a ton of bleed buildup) in Elden Ring. Get two of those, put Blood ashes on them to ramp up their procs, and just destroy the game. There's also the Beastman Curved Sword late in the game that has a similar effect and might be a little better, don't remember.
Should clarify that the Souls 1 hammer is from the GIANT blacksmith, not the Parish one. Would need to go back to the Parish one to upgrade it, after O&S. Can buy everything needed to max it out at +5 beforehand. Buy all the Twinkling Titanites needed from the Giant Blacksmith (10 I guess?) before slaying him for the hammer, go defeat O&S, warp back to Parish and max it out, roll the rest of the game.
Trying to decide if I want to do a NG+ with the hammer (i.e. go kill the guy at the end of my old NG file and start a NG+) OR try doing an SL1 run from the beginning and get the hammer/use it.
Problem is that it takes quite a bit of time to get to the hammer, the O&S area is like a third of the way through the game even if you beeline to it.
Edit: Also, the hammer requires 16 str to one-hand it, so it might not be usable on an SL1 run unless you two-hand it. Unless someone starts with 16 str, but then they probably won't be SL1, it would just be a "no leveling" run.