Blightsong
Would it be harder for Jasnah to Soulcast a Knight Radiant?
Brandon Sanderson
Yes.
Questioner
Would it be harder for her to Soulcast a Mistborn?
Brandon Sanderson
Yes, Investiture resists Investiture. It's harder for her to even Soulcast a person than a rock, right?
Questioner
Is a Mistborn Invested?
Brandon Sanderson
The Mistborn, while they're burning the metal. They are not specifically Invested when they are not burning. When the Investiture becomes active, then yes. Before, no.
Blightsong
So Kelsier, he stayed around longer, not because he was Invested, but because he had the potential to use Investiture?
Brandon Sanderson
Over time using the magic will Invest you, on Scadrial. Most of the power is not coming from, on Roshar the power isn't coming from the person either [he cut himself off, so I assume this is how it works on Scadrial even though he didn't finish his thought] so I'm going to have to back up on that one and say, yes, the Mistborn are as Invested as a Knight Radiant, because in both cases the majority, bulk, of the power is coming from somewhere else, but there is the Spiritweb. Investing the wrong term, but you have all these connections in the Spiritual Realm, so yanking you away from them, or rewriting them is harder.
Questioner
Would they be harder with more Stormlight or metals burning?
Brandon Sanderson
Yes, yes. That would increase the difficulty ratio. For instance, wearing Shardplate is gonna be a great barrier, right, and things like that so yeah. The problem is like, Invested is the wrong term for that, their Spiritweb is connected in different ways.