Yamata set bonus incorrect?

[PekingDuck13]

PSUpedia says that using the Yamata-misaki and Yamata-senba together gives you a 25% bonus on ATP and DFP, but I haven't noticed any difference in numbers. They are exactly the same in both damage I deal and take with or without both equipped at the same time. You would think that 25% would be a pretty noticeable difference. Is psupedia wrong? Can anyone confirm that it works, or does it give a different bonus from the one listed on psupedia?

I also find it very peculiar that the Yamata set is the only set listed to give a percentage boost when all of the other set bonuses are raw numbers.

[gryphonvii]

AOI=nerf from what I hear

[Pillan]

The boost might be incorrect. The original assumption was that the set bonus was a 25% boost to the weapon and armor stats (which somehow became a boost to total Atk/Def), but even that was proven incorrect later on. It varies entirely with the set itself.

Also, don't forget that the bonus might be smaller than the normal damage deviation. If the set only adds around 80 ATP and you have 1600 total, the damage increase is probably smaller than the damage variance you get each it.