I'm saying though, I want to see a Samurai who specializes in Jutsu and Iaido, Mifune just used his sword, and that "Iaido is so fast ninja can't use jutsu" crap is pure garbage, I wanna see a Samurai use fire style and lop somebody's head off.
That would make them ninja swordman,
the point of a samurai is to show an implicit skill on their sword.
Iado should not be underestimated, Sasuke was able to react against Mifune because of his sharingan, without his sharingan, he will be dead.
Most jutsu require handseals, and Samurai technique do not. Also, SSS is a powerful technique which can cut through A rank projectile jutsus such as fireballs, lightning, etc
Samurai don't use ninjutsu though. So for the way you'd like them to be they're absolutely a fail. They certainly aren't the least bit impressive.
What would Mifune do against a rasengan user who doesn't need hand seals?
That's because you dont know about them as much,
you do not realize how fast Iado is, and the lenght that SSS can have
Rasengan requires direct contact from a really short range,
A katana is longer for nature, meaning that samurais will reach target sooner.
Samurais have such fast movements, that 2T sharingan will need to be required to react to their movements easier. Hanzo had his weapon in the way, if he decided to continue his handseals, he would be dead,
Samurais obligate the ninja to only be able to use Tai and Ken, and maybe not so strong ninjutsu, but the ninja will need to retreat to do so, and a samurai will not be waiting for them to do so.