As far as I know it's WAI.
The status effect symbol on affected foes is added to the power differently from the debuff, so you can have powers that have animation but don't debuff, or vice versa. It's just the way the power system is (badly, IMO) designed.
Oh well, I suppose it's WAI.
in pvp your oppenent will have your defense has been reduced if that helps.
He will honor his words; he will definitely carry out his actions. What he promises he will fulfill. He does not care about his bodily self, putting his life and death aside to come forward for another's troubled besiegement. He does not boast about his ability, or shamelessly extol his own virtues. - Sima Qian.
I just created a Claws/SR scarpper and chose the 'Slash' power at lvl 4. The description of the power says it deals moderate damage and reduces the enemy defence, yet after using the power hundreds of times I have yet to see the def-debuff symbold pop up around any hit bad guys. It isn't a graphics problem with displaying the debuff symbol, as the damage debuff symbol from my Mutagen lvl 1-10 power works fine, and I can see all status effects any team members inflict upon them (including other def-debuffs).
Also - the combat tab does say "You hit target for x amount of damge, and reduce his defence!" when I land a hit on them with slash, but it's fairly obvious that it's just scripted to say that whether it really happens or not. (Admittedly I may be wrong, I'm not in the habit of having the combat tab displaying often)
Anyone got any idea as to whether this power is WAI or the description is wrong or what?