Keystone that makes off-hand slot unavailable?

I've always liked games where there is a possibility of creating a single-handed character. In particular, I like using characters that make use of a single dagger with empty offhand.

It would be cool if there were a keystone added to the passive tree that makes the off-hand slot unavailable and in return provides some bonuses.

it exists.
its called "shield"
it provides some blockchance, life, res and stats and doesnt work with a weapon EQ'd.

They wouldn't add a keystone like this tbh when it comes to weapons they group stuff up and you get overlap so not everything is completely useless.

For instance if i was wanting to go daggers, i have ele damage, generic phys damage, damage with daggers (also dual wield would work if i was using 2)

with that i could level with something else by grabbing generic phys damage or ele damage then transition into daggers once i have the right weapons, gear and build to support it.

But if you REALLY wanted to do 1 hand dagger (no shield or off hand) you have