TWF+Rogue Weapon Talent

[inati]

I would say no. If you had a +1 shortsword in your offhand, would it grant its bonuses to the main hand? Of course not. And as has been pointed out by others, the FAQ clears this up nicely

Regardless, I think it was the intention of the design team to give an incentive to actually use daggers to attack with, and not as a way to let players gain a +1 to attack by lugging it around in the offhand.

 

[Saeviomagy]

Would you also argue to up the damage die of the rogue's rapier to 1d10 if he held a shuriken in his offhand?

 

[calypso15]

Would you also argue to up the damage die of the rogue's rapier to 1d10 if he held a shuriken in his offhand?

It follows the same logic, but with one important exception: you can't use two-weapon fighting with a rapier+shuriken. You can't make melee attacks with ranged weapons.