The real difference between what Mesaana did and the examples the others have referenced is that Egwene, despite knowing the strong psychological nature of Tel'aran'rhiod, didn't REALIZE until almost too late that she was under attack. Similar to when Rahvin tries to change Rand into a beast that can't channel and Rand almost takes too long to figure out what's happening; that nearly succeeded because Rand didn't know it was possible, but Egwene would have recognized the trick immediately. Mesaana used a much less noticeable technique, so Egwenes first alert that something was amiss was approaching the precipice of total defeat. We've seen that the other Forsaken who confronted people there were fully aware and capable of using purely mental attacks, and Ishamael makes whole fortresses with his mind alone. Mesaana just took it to the next level.

Or did she...? I wonder quite a bit of channeling in T'a'r augments mental techniques, or perhaps they augment each other. Even in the waking world will is required to direct the flows, but just as a dog will twitch his paws, sometimes move his legs, when dreaming of a dead sprint chasing something, channeling, walking, talking etc. in T'a'r is primarily a mental exercise. I wonder if there's a true separation there, or if, say, an arrow made of Fire is more difficult to avoid or simply "unmake" than one made of simple wood, since one confronts not only the will of its maker, but the flows they used to create it. It makes a certain amount of sense, otherwise instead of weaving a shield around an opposing channeler you could just imagine the shield existing and it would. That would put the matter in a very different light, with the other Forsaken, those generally considered masters of Tel'aran'rhiod, knowing all the mental techniques will be that much more effective if aided by the One Power, while Mesaana thinks, far more simplistically, It's a purely mental world where channeling is possible, so I can use the One Power, but since the mind trumps all there, I shouldn't.