Quote if anyone is interested (Egwene testing the barrier on Callandor in Tel'aran'rhiod.

Cautiously, she reached out with the Power, probing at whatever held and shielded the sword. Her probe touched—something—and stopped. She could sense which of the Five Powers had been used here. Air, and Fire, and Spirit. She could trace the intricate weave made by saidar, set with a strength that amazed her. There were gaps in that weave, spaces where her probe should slide through. When she tried, it was like fighting the strongest part of the weave head on. It hit her then, what she was trying to force a way through, and she let her probe vanish. Half that wall had been woven using saidar; the other half, the part she could not sense or touch, had been made with saidin. That was not it, exactly—the wall was all of one piece—but it was close enough. A stone wall stops a blind woman as surely as one who can see it.

The Dragon Reborn, Chapter 27