What's the point of the Hattori Hanzo sword
If The Bride only actually used it to kill O'Ren, and not Bill or any of the other Deadly Vipers.
Hattori Hanzo made it seem like his weapon would be THE instrument to kill Bill, which was the only reason he agreed to break his oath to create the weapon.
And then Elle finishes Bill off with a secret kung-fu technique instead.
The sword really had very little significance overall by the end, and it became more about avenging Pai Mei and Beatrix being the actual worthy successor to Pai Mei's secret techniques.