For ages I've been looking for an RPG where you could viably use a weapon in one hand without needing a shield or another weapon in the other hand, this is so cool!
Who said that you do not need a shield?
Everybody using dagger and better or worse shield. It's stupid not use empty hand when game does not have any one-hand specialization or bonus. But daggers need dexterity and shields need strength. So specializing in daggers has a big disadvantage.
Therefore no, in this RPG you couldnt "viably" use a weapon in one hand without needing a shield or another weapon.