It does - see PHB p311.
My position on the two weapon thing is fairly simple. We know that it's possible to hold a greatsword without it being usable as a weapon - holding it in one hand will certainly achieve this.
We know that it's possible to hold an urgrosh without the spiked end being usable as a weapon - swinging the axe end to add 1.5x Str bonus to damage will certainly achieve this.
We know that it's possible to hold a shield without it being usable as a weapon - benefitting from the shield bonus to AC will do it.
My position is simply that this can be generalised - one can hold a weapon without wielding it. I can hold a dagger in my off-hand, just as I can hold a torch or a lantern, and not wield it - I thus am not wielding a second weapon in my off-hand, and take no penalties, but neither can I attack or threaten with it.
-Hyp.