What would happen if Nightblood clashed with another Nightblood?

[kroen]

Would they block each other effectively, or destroy each other, or would they act like two black holes colliding? (meaning they'll merge together into a single bigger/more invested blade.) 

Edited December 16, 2019 by kroen

[Quantus he/him]

Bad. Things.

 

Best case they'd annihilate each other, though for that to happen I think the other would need the another Destroy Evil Command, and time to accumulate Investiture the way Nightblood seems to have done, otherwise I think Nightblood would likely win the contest.  I tend to think any other command wouldnt provide the sort of complete destruction that Nightblood can, and that they'd need to be matched in power.

Worst case they rip a hole in the Realms, some sort of wild Perpendicularity.

[Weltall]

Brandon's said that the swords don't even need to be of equal power for Bad Things to happen:

Quote

Questioner

What would happen if Azure's sword was wielded against Nightblood?

Brandon Sanderson

If Azure's sword was wielded against Nightblood, terrible things would happen, but Nightblood would be the stronger of the pair. Good question.

Starsight Release Party (Nov. 26, 2019)

So imagining Nightblood versus an equally powerful Awakened weapon with a similar command, I'd probably want to be observing that from a good distance. Or from the Cognitive Realm. Or possibly both at once, just to be safe.

[Ixthos Luke/Luke]

I think Nightblood is fairly similar to a lump of uranium just below critical mass. The original nuclear bombs worked by slamming two such masses together.

[Karger he/him]

Assuming they are exactly equal in strength if they don't annihilate each other I would say nothing.

[Frustration]

I'ma say they would absorb everything in like a two mile radius in every realm and probably go inactive for years.

[StarrFall]

On 12/16/2019 at 5:28 PM, Ookla the Nameless said:

Brandon's said that the swords don't even need to be of equal power for Bad Things to happen:

So imagining Nightblood versus an equally powerful Awakened weapon with a similar command, I'd probably want to be observing that from a good distance. Or from the Cognitive Realm. Or possibly both at once, just to be safe.

Now I'm desperately hoping to see is Szeth and "Azure" square off in Stormlight 4...

[+robardin he/him]

Since Nightblood remembers people like Vivenna, and her sword is conscious enough to feel people out who draw it, do they "recognize" each other?

For that matter, does Nightblood recognize or talk to spren? Now that Szeth is of the Third Ideal, what if he draws NB while also summoning his Blade? Or even if he doesn't, but his spren is simply around?

[Wander89 he/him]

Nightception

[SirWolfe]

I feel like their Commands will try to overpower one another, and the blades will begin to consume the matter, investiture, and energy around them in an attempt to become stronger than the other. Eventually, one of the blades would win, essentially eating the other sword and overtaking its Command, but not before the surrounding area has been completely drained of matter and investiture.