2.3.04: How do One-Power-forged blades work?
I asked RJ about Aes Sedai-forged weapons, like Lan's sword that never needs sharpening: was the Power just used in the manufacturing process, to change the structure of the steel to make it extra-strong, or was a flow of the Power somehow incorporated into the steel? "The Power was used in blending the metals (and other materials...) and altering the structure. There is no source of the Power in these weapons, nor do they draw on the Power like angreal...." [from RJ letter 4/95]
In the same letter, RJ said that when a Fadeblade strikes Power-wrought metal, the reaction produces blue sparks. This implies that Fadeblades are Power-wrought metal, as when we see the two Fades dueling during the fight in the Stone in [TSR: 10, The Stone Stands, 135].
This also implies that Thom Merrilin had Power-wrought daggers during the incident in Whitebridge [TEOTW: 26, Whitebridge, 318], which has always struck most people as rather odd. RJ addressed this question in the post-WH Dromen & Demonen chat:
Q: If a Fade's blade will not produce lightning except against other Thakandar-wrought blades, and Power-wrought blades, why do Thom's daggers produce it when he attacks the Fade at Whitebridge?
RJ: Thom's daggers did not produce the effect. It was produced before Thom reached the Fade.
Steven Cooper remarks, "Having checked [the passage], RJ is not quite right in saying the effect was produced before Thom reached the Fade - first Thom crashes into the Fade, then 'The air in the square flashed an eye-searing blue'. However, it certainly seems from this response that RJ never intended to give the impression that Thom had OP-wrought daggers."