^u have to remember that mifune is no peon LOL the reason why danzo use KA on mifune because he want to become the commander of the joint shinobi allied forces so that he can rule the world after the war end,
and danzo was never intended to fight sasuke at that time, since when sasuke show up he immediately retreat, but sadly tobi find him and make him fight sasuke, at that time danzo was underestimating the uchiha brat and confident enough just because he has more sharingan LOL, the only thing that worry him at that time is tobi and he was planning to spam izanagi until his right eye vision prowess return, so that he can use it on tobi, but sadly sasuke know about izanagi and manage to outsmart danzo in the end,
but if it was 1 vs 1 and danzo don't have to worry about tobi, then he can beat sasuke with med difficulty