I mean, really, what's to prevent me from taking LostSoul's example and changing it to "The fighter gets up, dances a little jig around the room, stubs his toes, and falls over where he was before. He seems to be winking at the elf."?
Because that would be silly. Which would be all right if you were going for a silly theme, but for standard fantasy adventure it's kind of out of genre.
Try this for a not-silly narrative of the same effect: There's a game on the Playstation 3 that had a demo I played in a store back when they released the system. It's a boxing game, and as you are pummelled by your opponent your vision starts to haze over, and redness seeps in from the edges, until finally you get a kind of tunnel vision that looks not unlike what happens in a migraine. I don't know how accurate this is as a representation of blunt trauma to the head, but it works for me as a decent depiction of why you're having trouble blocking and punching.
When you get hit enough times, you go down, and the ref starts to count. The visuals are blurry and indistinct, and the audio sounds like you're underwater. Getting back up feels like a real struggle, and when you do, you shake off some of the blurriness. Eventually, you don't get up at all, unless you win (which is extremely unlikely). I kind of imagine that instead of hearing the ref counting, and thereby being motivated to stand, a 4e character might hear the warlord shouting something extremely motivating and uplifting, that causes the character to choke it down, grit his teeth, and stand, perhaps almost automatically, as soldiers are said to do when they hear orders (whatever fits with the character). He shakes off some of the noise and fire in his head, and keeps fighting.
In other words, he was reduced to 0 HP, became unconscious, and then received an inspiring word. He was unconscious, which in this case meant that he was unable to act, face down, barely able to open his eyes, and his head was swimming with pain and blood pressure. He was just barely capable of hearing the warlord screaming at him to "move, damn it! Move!" before he slipped away completely.
This explanation of "unconscious" sounds just fine to me. I could also point out that I'm no stranger to unconsciousness, having gone through a period of fainting spells when I was a teenager. During these spells, I would be barely able to perceive what was going on around me, in a manner not unlike being awakened by someone talking to you while you're asleep. At first, you perceive the sound, but aren't exactly aware of it. Then you become aware of it, and then you remember that you've been hearing it for some time now. At this point, you've put together a thought coherent enough to rouse your brain into activity, and you wake up. Again, if the sound of talking is actually the warlord's practised banter helping you to find your way back to consciousness, it seems to fit both the rules and the descriptor just fine.
