Board Thread:Dark Souls II/@comment-107.171.159.173-20140906202200/@comment-5264386-20140907020934

I'd say the Shadow Dagger would be better, as it scales with Strength and Dexterity (C/D scaling), whereas the Bandit Knife only has a D scaling rank in Strength. In addition to this, since Strength provides about double the bonus of Dexterity (e.g. 20 Strength is equivalent to having 40 Dexterity), you should be able to get a nice amount of damage from the Shadow Dagger.