was bedeuten defense modofier ? zb in ac oder add all def 20`?

huh?

so, the crit decrease is a percentage? does that mean that if you have a crit chance of 10%, upon running this special it drops to 8%?

The crit decrease is for the enemy, i.e. his/her chance to make critical hits on you will be lower.

No, it's User percentage dropped down 2%.
You're correct dzdaddy.

"Critical decrease" is an entirely different thing than "CriticalIncrease", if it would reduce the criticalchance of the player that perked this, it would say "User Modify CriticalIncrease -2"

to back up Wizardi here (Enfo = clueless on this one) ... "CritDecrease 2" means the mob you are attack loses 2% of his critchance. Since most mobs have a CritChance of 3 or so like players start with, it means it can cut out around 66% of the crits you take from normal mobs. Of course, some mobs have much higher crit chance, and the biggest value here is lowering crit chance from PVP. Most classes have very little CritDecrease available to them, maybe a Spirit Shroud or Bigot's Earring. Only Fixers through this line (which was created specially this way to prevent Fixers from using it + GA) and Crat/MA/Shade via Careful in Battle get such a massive crit decrease.