It takes a 1/2 action to attack, but I think the book says you need the 2 Weapon talent to attack with 2 weapons in one round. Is the latter right?

Correct,

While anyone can wield two weapons and select the one they wish to attack with, they need the Two-Weapon Fighting Talent to attack with both weapons in the same round. Source, page 244 in the Core book.

"If you do not have the Two Weapon Wielder talent and you wield
two weapons at the same time, you can use a Full Action to make a
single attack with each weapon. However, you suffer a –20 to the
attack roll with the weapon in your dominant hand and –40 with
the weapon in your off hand."

page 11, Errata 3.0

Ambidextrous changes this as well, reducing the difficulty of each hand

And yet, you can only get a +0 for dual-wielding if you use swords. Even if you're using lightning claws, which were specifically designed to be dual-wielded.