Dawnshards and Anti-Light

[kelianmao]

Anti-Light clearly has roots in our universe's antimatter, e.g. having the same properties as regular Light, except with polarity reversed, and annihilating on contact with its regular counterpart. The addition of Intent is where the parallels diverge; in our universe, conservation laws forbid the direct conversion of matter to antimatter. In the Cosmere, however, you can clearly change Light into its anti-Light through the use of Intent, as discovered by Navani in RoW. So, it seems Intent is necessary to change Light to anti-Light, Investiture to anti-Investiture.

However, Navani notes that the inverted tone used to create anti-Light sounds exactly the same as the regular tone, except with the addition of Intent. At the time she does this, she is not yet Radiant or otherwise Invested. There were also no fabrials involved, which are Invested due to their trapped spren. 
Proposition: Intent is sufficient to change Light to anti-Light; Investiture is not needed to power it, unlike usual acts of Cosmere magic. Indeed, requiring Investiture may be counter-productive, since we are aiming to produce the opposite of Investiture.

Now consider: Dawnshards are god-level Commands, essentially the ability to super-charge Intent. The "change" Dawnshard is right here on Roshar, held by (or is) Rysn. The Sleepless allowed Rysn to live, under the condition that she never bond a Radiant spren. The idea behind this seems most likely to be to ensure that she never has access to Investiture to power the Dawnshard. But if changing Light to anti-Light only requires Intent...

Conclusion: Rysn is now completely OP. Imagine she Commands half of Odium to change into anti-Odium. Boom, no more Odium (and probably no more Roshar). Or, if she just changes the entire Rosharan system to 100% anti-Investiture, then Odium is trapped there, unable to interact with the rest of the Cosmere lest he goes boom. He can't even interact remotely since all those methods involve Investiture.

[Frustration]

The Dawnshard is mostly useless without access to Investiture, and even with it she couldn't change Odium.

Edited April 5, 2022 by Frustration

[cometaryorbit]

I doubt the Investiture making up a Shard itself is "accessible" to that kind of change. She'd need half of Odium trapped as Voidlight in gems, and there's probably not enough gems in the entire Cosmere to do that.

The Light alteration doesn't rely on a Radiant bond, so Rysn could do that, but maybe not better than anyone else (though, OTOH, the Heightening like effects of the Dawnshard might give her some intuitive understanding... but I doubt it would be super dramatic.)