Frequently Asked Questions:
A: This adds little to the game that simply training HP (or AS, or protection, or endurance...) doesn't.
A: Because two good 1HW like an ELS or maybe even two claymores would be massively overpowered. Getting even one extra attack would be way more benefit than using a shield or a 2HW, so a lot of gameplay choice would be lost (because one option is far more powerful than the others).
Now, we could make twoweapon a Skill, but then we'd get rid of Bloodlust and only people who could afford to upgrade two weapons would have that choice. I think it's better the way it is.