This game has a lack of moves compared to other fighting games like street fighter and so on so it can be difficult to counter certain moves because their are no counters to them. For example some players have knock down moves where you don't need to lose your stamina first in order to be knocked down such as the centurion Also some characters have non-stop bashing attacks which they can chain and can't be countered. Also some characters have sweep attacks in which they can't be countered such as the valkyrie.
One thing I dislike is when your knocked on the floor you can't get up quickly so you end up eating a heavy attack. These are non-stop occurences by the OP players listed below.
The easiest most OP units in this game are Kensei, Orochi, Aramusha "very fast attacks, do a lot of damage for a non-large character. Berserker, "does high damage for a non-large character, can die in 3 hits or less". Centurion, "has too many easy to do stun attacks, also can knock players to the floor without them losing stamina first, and does a extremely high damage stab attack to knocked down player which you can lose 2 bars of health.
Because this game has a lack moves some characters will always be OP unless they are nerfed in some.