Which is why my reasoning about either creating a specialized build, or a diverse build. People talk about the “NEW” class advancement system causes imbalance, while there’s still a lot we need to sacrifice for the build that we want to actually build.
As you said, Swordsman C3 -> Rodelero won’t be able to do manual blocking and no Swash Buckling to aggro enemies either. However, you get tons of CC and can and able to lock them down to death.
Swordsman C3 -> Cataphract will lose Finestra, Synchro Thrusting, Pierce, and Stabbing - which are really essential if you want to build a High DPS Cataphract. However, if your restrain proc-ed, then you can caught up to them really fast even without Trot, providing the enemy trying to run away.
As for Barbarian: You don’t need to go Barbarian C3 to get Cleave and Helm Chopper - You can get them in Barbarian C1, and it opens up your build to go Corsair C2 but you will lose but you will lose Seism, War Cry, and Frenzy; or go Barbarian C2 and retain those 3 C2 skills and then go Doppel for Deeds of Valor. - This build probably the best bet to create a high DPS build while still retaining your Swordsman C3.