Wargear in question is on Page 54 of the codex, and it reads, "The wielder of a pair of Nemesis Falchions has +1 attack."
Quickly flipping through, it appears this upgrade costs between 5-15 points, depending on the model.
I believe the GKs get +1 attack total, not +2. Just a belief, not a hard fact. There won't be any hard facts until that beautiful FAQ lands. It would be really nice if GW started beta testing...