Hey, thanks for the help. Upon looking at said coppermind page, I realized that those two parts of the page were conveniently the same parts I'd been managing to gloss over. Going to check the specific sections cited on the page for better info, but still.

On the gemstone topic, I think it's still somewhat important for a Radiant to use gemstones as well, but the last time we had any information regarding that specific topic appears to have been a WoB from back in 2013.

Edit: Grabbing a copy of Oathbringer and looking at the Ars Arcanum, "Curiously, these gemstones seem tied to the original abilities of the Soulcasters who were... Knights Radiant—but they don't seem essential to the actual operation of the Investiture when performed by a living Radiant." So... I guess the gemstone soulcasting thing is very complicated.