Anri's straight sword seems hopeless

[Kantarza]

I decided to try out a challenge game and run a luck-only build. I picked up Anri's straight sword after seeing so many glowing articles but when I picked it up it was unimpressive. I've got 40 luck and 10 str/dex/fth but AR is only 191.

I was anticipating a rocking 390-odd as depicted in online tools, videos and discussions. Is it still plausible to do a luck-only build and what should I use instead? I'm not yet ready to go full SL1.