Quote from xeare;1286363:
Based on how flattened Girg was after being hit with judgement blade that many times with, what I'm assuming is, a bunch of high ranked Breaking Lies and the difficult nature of obtaining the skill and all sorts of stuff, I'm pretty convinced that the 3% reduction is for the crazy 98% damage reduction he has innately.
And it would make sense too, as 3% extra damage wouldn't seem worth your time, but it's actual effect at max rank is more than doubling your base DPS against Girg with the first blade, so it makes a bunch more sense like that.
Girgashiy has 125 Protection Stat/70% Effective Protection, or however the Enlightenment changes work for monsters. The damage reduction is 96%, not 98%, and that is added after the Protection reduction.
Judgment Blade itself ignores 35% of the 96% damage reduction in the "Crusader Combo", and at the same time it gives Girgashiy a 10 sec~ debuff where he loses the same amount of damage reduction, meaning that everyone in the raid does more damage with their own attacks. However, no one's ever figured out how it's calculated (whether its a direct subtraction or some other complicated outcome), and how Breaking Lies works (whether it directly subtracts or amplifies Judgment Blade's damage reduction ignore/reduce effect, or some other complicated outcome).