Why does Shallan have geolocation?

[Seloun]

During the pre-release, Shallan's perfect sense of direction immediately jumped out at me:

Quote

They led her through the streets quickly, the hood still on. Shallan took over, as she had an incredible—likely supernatural—ability to sense and memorize direction. She mapped their path in her head. Sneaky little cremlings; they led her in a large double loop, ending at a location near where they’d emerged from the cellar.

Sanderson, Brandon. Rhythm of War (The Stormlight Archive) . Tom Doherty Associates. Kindle Edition. 

The reason for this is because geolocation was the hypothesis for the Elsecaller resonance based off of the end of WoR, where it looks like Jasnah knows exactly where to go despite being dropped in the middle of the wilderness (and because it seems like the natural thing to associate with someone who can travel magically):

Quote

She looked him up and down, then drew her lips to a line and nodded. She started walking directly toward the nearest town. She had a good sense of direction, this woman.

Wit strolled up beside her. “You realize we’re at least a week away from civilization. Did you need to Elsecall this far out in the middle of nowhere?”

Sanderson, Brandon. Words of Radiance (Stormlight Archive, The) (p. 1079). Tom Doherty Associates. Kindle Edition. 

So my immediate, WAG was that somehow Shallan had also been bound as an Elsecaller, which would potentially be hard to distinguish since they share similar abilities to Lightweavers, or possibly affected by her interactions with the Unmade. I actually misread the original interaction with the deadeye Adolin runs into (I thought it was an inkspren, since I was looking for one, and not a cryptic), which I thought explained it...

But of course, that's not actually what appears to have happened. So the question still remains - why does Shallan have geolocation?

The resonance of Memory appears to be the established one for Lightweavers. It's possible that the geolocation Resonance is just an extension of that ('memorize direction') or that this ability is actually distinct from the one Jasnah appears to have (knowing where you've been - odometry - is not the same as knowing where you are relative to a global frame), but the two abilities seem pretty close, colloquially (it's also possible Jasnah just knew the direction to go, similar to what Shallan seems to experience, rather than explicitly knowing where she was). There doesn't seem to be any evidence that any other Lightweaver exhibits this, either, though the evidence is scant (to the point of non-existence?) in either direction. If any other Lightweavers did exhibit this, it seems like it would be something that would have come up during Shallan's internal description, though.

One important consideration is that Shallan does seem to have at least one power the other Lightweavers don't have yet. Despite being a poor-to-mediocre Soulcaster (at least, doing it Jasnah's way...), Shallan can cross over to Shadesmar:

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Many of the gatekeepers maintained this rule. However, a few had listened to the Stormfather’s request. They said that in the absence of other Bondsmiths, Dalinar and the Stormfather were worthy of obedience—even in contradiction of ancient orders.

That was fortunate, for while Shallan could slip into Shadesmar using her powers, she couldn’t take anyone with her—and she couldn’t return on her own. Even Jasnah, whose powers supposedly allowed it, had trouble bringing herself back from Shadesmar.

Sanderson, Brandon. Rhythm of War (The Stormlight Archive) . Tom Doherty Associates. Kindle Edition. 

It specifically mention Shallan, despite there being three other Lightweavers going with her, which seems to imply this is something only Shallan can do out of the Lightweavers. And Jasnah can as well, of course, so it might be that the geolocation Resonance is somehow tied to being able to transport to Shadesmar (as an aside, Shallan having this ability actually seems really weird, since transportation to Shadesmar sounds more like Translocation than Soulcasting, but there isn't anything that seems to indicate that e.g. Jasnah finds this unusual). This could make sense if the person could somehow use their sense of position in Shadesmar to help determine their position/orientation in the Physical as well.

[Elsecaller_17.5 he/him]

I don't think its true geolocation at all, just an offshoot of her memory powers.  If i'm not mistaken Shallan took over at the point spefically to trace their path.

[Seloun]

It's possible that what Shallan is doing here is different from what Jasnah is doing at the end of WoR (which includes the possibility Jasnah wasn't exhibiting anything supernatural, though Wit's comment seems to imply otherwise). However, as noted in the OP, other Lightweavers don't seem to exhibit this ability, so I don't know that it's just an aspect of Memory. It might be worth noting that Shallan seemed to exhibit a form of this during WoR - her sense of direction when in the chasms seemed to be much better than Kaladin's, who was certainly much more familiar with the chasms in general than she was.

[Kingsdaughter613 she/her]

Shallan also is technically bonded to two Cryptics (she still seems to have a kind-of bond with Testament), which may mean her powers act differently.

[Seloun]

9 hours ago, Kingsdaughter613 said:

Shallan also is technically bonded to two Cryptics (she still seems to have a kind-of bond with Testament), which may mean her powers act differently.

While that's possible, it seems like it would be odd if that led to different Resonances, since those are specifically from mixture of surges. It would mean bonding two of the same type of spren somehow granted different surges (assuming Jasnah and Shallan are demonstrating the same Resonance here).

[Kingsdaughter613 she/her]

Just now, Seloun said:

While that's possible, it seems like it would be odd if that led to different Resonances, since those are specifically from mixture of surges. It would mean bonding two of the same type of spren somehow granted different surges (assuming Jasnah and Shallan are demonstrating the same Resonance here).

Or it could increase the power of her resonance. I’d think it would effect the strength of her powers.

[Argel he/him]

Could also be due to experience --  she's been a Lightweaver since childhood.

[Subvisual Haze]

Maps are art, and Brandon likes piling cool artist skills onto Shallan.