I don’t think it works like this, From what I understand the damage, health, stamina depend on the character level, the class level is separated and you only need to unlock the Traits. Therefore you will deal the correct damage.
I understand that if you want a specific effect you might be forced to use a weapon you don’t like, but in my opinion it’s much better than a system like the enchantment system which is actually just RNG, you play a bit with the weapon you don’t like and then you have the trait you want forever.
This system is not new, it has already been used in Final Fantasy Tactics, all the people who have played this game seem to be very happy that this system is being implemented, in Final Fantasy Tactics is called the “job system”.
If you want to ask questions you could ask them here: PSA - An overview of the upcoming class system