Protector: A fighter with a high block ratio
Specialist: A fighter who deals true damage(Some of the hits will be regular but the others will deal true damage)
Swift Striker: A fighter who attacks faster than most
Tank: A fighter with a chance of counter or deflect(If hit by projectile)
Cannon: A fighter who pushes back whoever they hit when passive is activated
Protector should be Tank, aswell as Tank should be Protector. It would fit the names better, as a Tank is supposed to 'Tank' the damage, thus blocking, while a Protector is supposed to 'protect themself' from damage, thus countering/deflecting.
Specialist shouldn't deal True Damage, that can be highly abused. (True damage means that the damage is an exact number, regardless of the enemies defense and armor.)
Swift Striker should be removed, as it can not only be highly overpowered but also highly underpowered. It's impossible to find a balanced speed, unless you've got a 'luck' system running.
Cannon sounds good, though their knockback should do half the normal damage, but twice the damage if the ones you push, hits a densed object.
-Double Up-
The user's passive allows them to randomly strike twice.
-Sinister strike-
The user's passive allows them to hit more precisely, granting them an extra chance of doing critical hits.
-Swift wind-
The user can move 20% faster and hit 10% faster.
-Dead's end-
The user got a slightly increase in block ratio, aswell as a boost in Health and regeneration.