[WaT] Taln Dawnshard Theory

I theorize that one of the two unknown Dawnshards has the command 'Bind'. I believe this Dawnshard was involved in the destruction of Ashyn. Then later on Roshar, Taln briefly held this Dawnshard. Using the Dawnshard he tried to kill Cultivation, failed, and lost the Dawnshard to her.

We learn in chapter 65 of WaT that Taln's soul has been warped from his attempt to kill Cultivation.

“His soul is warped,” Jezrien said, “from his attempt to kill Cultivation.

I first assumed that Cultivation warped his soul in the conflict when Taln attacked her. But what if his soul was warped before he attacked her? I don’t think Taln would attack Cultivation without a weapon he thought was capable of actually doing the job. Other soul warpings we've seen in the cosmere would include other current and former Dawnshard holders as we know holding a Dawnshard warps the soul of the vessel due to the massive amount of investiture. We learn later in this chapter that Taln has lost a weapon given to him by Kalak.

“Talenel,” Nale said, “this is Honor.” Taln frowned. He did not bow or show reverence, and instead looked the god straight in the eyes. ”I’ve waited a long time for this moment. And here I am. Without my weapon.”
“This one?” Honor asked. “You know what he did.”
”You wanted someone who’s had interaction with the gods,” Nale said. “Plus, I want contrary opinions in the group. For balance.”
Taln was still staring eye to eye with Honor. “You destroyed an entire world. My grandmother’s world.”
“I … regret that,” Honor said. “I vow—upon my own power—that I will not allow such destruction again.”
Taln stood a moment. When he spoke, his tone was cool. “Well, I suppose everyone deserves a second chance, even gods.” He stepped back to soothe a horse as a rumble of thunder sounded in the sky.
Dalinar couldn’t help walking up beside him. “You aren’t what I expected,” he said. Taln narrowed his eyes at him. “What? Still frustrated I lost the weapon you gave me, Kalak?”

I think this weapon Taln lost was the Bind Dawnshard. The only reference we have to a Dawnshard related to binding is from the Poem of Ista in the chapter 36 epigraph from Way of Kings.

“Taking the Dawnshard, known to bind any creature voidish or mortal, he crawled up the steps crafted for Heralds, ten strides tall apiece, toward the grand temple above."

I believe this poem is a future mytholigized version of Taln's attempt at using the Bind Dawnshard to kill Cultivation. The poem isn't entirely accurate, as Taln trying to kill Cultivation would have been prior to him becoming a herald and Cultivation isn't one for grand temples. But this could have been a mytholigized version of Taln's attempt crawling around the Valley to get to strike at Cultivation.

We also know that a Dawnshard was involved in the burning of Ashyn. However, the two Dawnshards we know, 'Exist' and 'Change' don't really strike me as commands that relate to the destruction we see on Ashyn. However, I could see the surge of Cohesion used alongside the power of a Bind Dawnshard to mess with the binding of an axi which could create a chain-reaction that caused the massive destruction that Ashyn went through. The cosmere mechanics version of an atom being split and creating a nuclear fission. To support my idea that the 'Bind' Dawnshard helped cause the destruction of Ashyn, then was brought to Roshar after for Taln to eventually receive Kriss discusses the idea of manipulating the forces of axi from the RoW ars arcanum.

“This ability manipulates the Surge of Cohesion, and is in many ways a cousin to the axial manipulation known as microkinesis—as both grant the ability to manipulate the forces that bind individual axi together. Fortunately, in my explorations, it appears that Stoneshaping is far less … explosive of a power, bounded by the rules that Honor placed upon it to protect from the mistakes that happened on Yolen.”

I reckon that Ashyn also experienced some mistakes involving the binding of individual axi and explosions. After the exodus to Roshar the Heralds brought this Dawnshard over from Ashyn and it eventually ended up in Taln's hands for him to try to use against Cultivation. He failed, leading to Cultivation to take the 'Bind' Dawnshard from him. What she did with the 'Bind' Dawnshard I am not sure of, but I reckon she was done having it be in humans hands after the destruction of Ashyn and the attempt on her life.

As a bonus I wonder if the warping of Taln's soul also helped him not break during the torture from the oathpact. He bound himself to the oathpact, and the warping of his soul from the 'Bind' Dawnshard meant he couldn't break his binding oath in the way the other Heralds could.

TL:DR The 'Bind' Dawnshard helped cause the destruction of Ashyn. It was brought to Roshar during the exodus. Later Kalak gave the 'Bind' Dawnshard to Taln who tried to use it to kill Cultivation. He failed and she stripped him of the weapon.