Bloody slash or blood blade?

so il start upgrading vigor and arcane 1 and 1( like if i get 2 level ups 1 in vigor one in arc,if i get 8 then 4 and 4) until 50 vigor and arounf 30 dex for a bleed build,only thing is im using nagakiba with double shlash and bloodflame so it doesnt scale with bleed so i either:

1 swap to nagakiba with bloody slash or blood blade and which of the two is better??

2 just use rob which im abt to get since its aow is basically double slash and it has like bloodflame blade build in

so which do i choose?