I mean, if there are any other samurai on a similar level to the scabbards, and we take into account that the scabbards are technicaly part of Wano's army, that's a very strong army after they were shown to be able to pierce Kaido's body.Akainu referred to wano's samurai as an unknown. For the most par there hasn't been official contact between the marines and wano samurai in potentially hundreds of years... It doesn't look like wano has THAT powerful an army though. Strong by individual nation standards apparently but not so much that they can face a yonko's crew. At least going by how kaido threatened them considering that 5k mimawarigumi and 5k oniwabanshu were at onigashima and kaido could have presumably ended them.
That's much stronger than Dressrosa's or Arabasta's armies.
pimp'n