blastwave only dazes, it does not stun. a daze is a snare debuff that does nothing but slow movement speed. like frostbolt, wing clip, earthbind totem or hamstring. it does not stop you from acting.
to elaborate more on the subject:
a stun will not break if you take damage, you are unable to act until it wears out. examples of this are cheap shot, kidney shot, hammer of justice, intercept stun, feral charge. mages can blink out of these.
an incapacitate effect will make you unable to act but will break on damage. gouge, repentance and maim are incapacitates (although gouge is not classified like this so it works in instances more). sleeps like hybernate and wyvern sting are also incapacitate effects.
disorients are a subgroup to incapacitate effects, in that you cannot act but your char moves around a bit. dragon's breath, scatter shot and blind are disorient effects. sheep is a special disorient because you also regain health while it is active. mages cannot blink out of these as they are NOT stuns.
some stuns come with an added immunity, so the target is completely unable to move but also immune to damage. examples are cyclone and banish.
a root means you can still cast and turn, but are unable to move from the spot. examples are frost nova and entangling roots.
edit: typo removed.
Edited, Jul 16th 2008 11:17am by Turicus