18th Shard

Yep, Talmut is Taln. As for the aluminum, it blocks the magic ability to cut through anything. Without that, it's a matter of if a normal sword can cut through the shield/mace. Shardbearers don't tend to swing the Blade like a huge heavy weapon, because it's harder to control it, so while it might scratch the aluminum, it's either not deep enough to cut through or the gap is too small for the Blade to get into the interior and actually cut it. You will see a moment where someone cuts through something aluminum with a Blade later, and they talk about how it works a little.

I've always (headcanon) thought the floor was just a massive manifestation of a bead for Roshar itself.

I think the whole manifesting Radiant in Shadesmar is not part of the Surge of Illumination, the Lightweaving we've seen Shallan do. It's more likely related to Soulcasting and Transformation.

Absolutely! I'm not sure how quick my response time would be, but tat would be great.

Disclaimer: Topologically speaking, there's only inside and outside. Your front is continuous with your back, and under appropriate spiking may not preserve the current proportions or shapes. Standard DA disclaimer applies.

I think the relevant question here is whether adding Investiture to a metalmind makes it (even infinitesimally) more massive. I think it would. Adding energy (kinetic, potential, or thermal) to something increases its mass a little bit, and massive concentrations of Investiture, like a perpendicularity, can cause some time dilation. E^2=(mc^2)^2+(pc)^2 really is saying that any energy added to a system increases either its mass or momentum. Adding an Investiture term should really just describe the same thing. In that case, I would think it would be something like: (E/c)^2+(I/k)^2=(mc)^2+p^2, where k is an arbitrary constant to get Investiture in compatible units at the right ratio. Edit: Or perhaps (E/c)^2=(mc)^2+p^2+(Ik)^2 + i^2, where I is passive Investiture and i is kinetic Investiture, analogous to rest mass and momentum.

You are correct. Post updated to reflect that.

"That's alright; I will wait. I don't believe any information I have should be acted on urgently. Careful consideration is necessary for action on any sensitive information." Xanas stepped in front of a seat. "Do you have any paperwork or binding contracts I should sign? I can fill those out as I wait; then we could have a notary or a guild representative handle any business which does not require Ms. Sheneth's personal attention." Xanas started sitting down, then paused, straightening. "I don't believe I ever got your name, nor your spren's. My apologies. My own is Xanas Khaevarin." As he was sitting, a woman rushed in the building. She paused when she saw him. "Um." @mathiau @Rushu42

Yeah, I picked the most entertaining one to respond with. Here's a selection of the various answers over the years.

Xanas Khaeverin - The Scholar's Guild A young, bald Terrisman looked up at Xanas, squinting at him. As Xanas spoke, he inhaled in some Stormlight. "Is this about the Forgery?" he asked. "I suppose so, yes," Xanas answered. "Among other things. For the past few millennia, I have been the Head of the Department of Testing and Analysis in the Dark Alleys, though there have been some lengthy leaves of absence in that time. I want to help advance the knowledge of the people of the city using what I have learned in that time. Spreading knowledge has ever been my goal, but the Alleys have slowly drifted away from that goal toward the insular acquisition of power and control. The Forgery is merely the latest example. I once made an oath to seek correct questions before seeking their answers, so I've come here, to the Scholar's Guild, and I hope that those here are interested in seeking those questions as well. To that end, I will share what I know about the Forgery and the Alleys. Whom should I speak with?" @mathiau

So similar to the above abilities from Breath, but broadened to all Investiture sources?