How many +A do Grey Knights Falchions Grant

We also need a ruling on the falchions on whether or not they grant only +1 attack for just their special rule and not include the paired +1A. Or does it grant +2A, 1 for its special rule and one for the two sccw rule.

Description is a pair of NFW...not two NFW. Indicating a single weapon selection.
There are also a few descriptions in the book (Master Crafted comes to mind) that indicates them to be a single selection as well.

Purifiers with Falchions would be getting 5 attacks (2+1+1+1) on the charge...I don't believe that was the intent.

Curious what the ruling is for CAG Makari?

why oh why does GW test me so.

Yes a pair means 2... but RAW seems to indicate that you need 2 special weapons to get a +1 attack. They may have worded it so that it restricts it to just +1.
I will confer again on this one but I'm leaning towards the +1. I am looking for other instances that support one way or the other.

If I remember correctly for the maser crafted it states only one of them can benefit from master-crafted indicating 2 weapons.

I don't have time to look at this very closely right ATM, but I know there has been a similar debate over Marneus Calgar's Gauntlets of Ultramar. The Space Marine codex is unclear whether to count "Gauntlets of Ultramar" as one weapon, or two separate weapons. Most people give him the +1A for having two weapons. If you give it to Marneus then by that precedent you should give it to the Grey Knights too.