Because Threadcutter says the wielder's damage value is 2, does bracers of the giant modify that to a three?

Yes. it does. The 2 replaces the damage on the dial. After that, everything else works as normal.

Ironwolf, threadcutter, BOG is a good long range 15 attack for 5 damage. Of course if you are not careful, next turn he is toast

try PATHIS ARCANA, Threadcutter, and BoG for 12" range for 5 damage to all figures with the same name...swarm armies beware...i used this versus a zombie swarm and mowed them down by turn 5 or 6...also, take note that PATHIS has ZERO Damage on her first click (with weapons master)...

ooops...i meant to say 4 damage at range and a 3 base damage...

I don't have a pathis, gaunt, malava from sorcery, only figures i need, so that won't work. Thanks i want to try having Prince Warden on Skydancer w/ Threadcutter and the BoG, for a possible total of six clicks of crushing blow to one figure, and three to figures of the same type becasue of threadcutter, You guys were a great help

can impale for five, five to every figure from the threadcutter, that would just be terribly awesome?

Yes.
Of course most riders have only six clicks of life and relatively low defense. To get that much damage odds on you MC/C across the board with a token. So now you are pushed in enemy country. That gives you opponent 2 turns to do 6 clicks killing the weilder. Which inturn returns all the named figures back to full health.

More than once, I have been one 8+ roll away from being swarmed under by the same swarm that I had just hit so hard.