Why Did Honor's Perpendicularity Move Around?

[Returned he/him]

This is the least of the revelations given or dangled from WaT but I was hoping for some kind of explanation about this. Why did Honor's perpendicularity move around over Roshar? No others seem to work that way, and I'd imagine fussy Honor's physical manifestation of divinity to be one of the most reliable.

I'd been thinking that maybe it had something to do with being a part of the storm, but that seems like a tenuous connection to me, especially because the Highstorms were (usually) so regular. It doesn't seem like it can be related to Tanavast being in turmoil with Honor's power, otherwise we'd expect similar mobility from Odium's well and that one explicitly stayed put for ages. Honor's splintering seems unlikely, as the pool in Elantris seemed to have a single location (though Elantris is early enough that it might not be 100% canon-able for really specific details). Cultivation's was stably located, so Investment into spren doesn't seem like a strong guess. Ambition's seems like the most comparable case, but in addition to not having the same properties I can't think of why they would be similar in this (or any) way.

Arbitrary plot reasons don't even seem good because the movement is so specifically undefined, only that it was unstable and dangerous; it could just as easily have been at the bottom of the ocean or otherwise inaccessible.

So what gives? Have I missed a detail somewhere that gives some insight into the matter? If not, what other guesses do people have?

[therunner he/him]

I think it was due to Honor not having a vessel, and so lacked proper Connection to Physical Realm.

It still had some, as it's power suffused Roshar, but not enough to stabilize Perpendicularity.

But I do agree it is not fully clear.

[Aon Tia she/her]

I think that Honor chose to hide his perpendicularity in the highstorm because a) it gives him the ability to provide stormlight to everyone on this world and b) more importantly it was a security measure. 

Shards, it seems, have to have a place where their power coalesces and these shardpool are a security hazard. They act as perpendicularities and allow all host of people  easy access to your planet and vice versa. I think shards do like to keep a tight leash on who comes and who goes. But I also think that these shardpools are vulnerability of the shard. Too easy an access to one, can allow some with enough knowledge to partake of their power and create a lot of mess. 

In a world like Roshar, where there are 2 shards, cultivation already has her perpendicularity at the horneater peaks, she has tried to make it as difficult to access as it is possible to make, Honor probably decided that a second stable perpendicularity will simply be too big a liability. 

Odium did try to hide his perpendicularity but as we now know there have been people who found out about it and used it for their purposes. 

whereas Honor's moving perpendicularity so far has proved to be most secure and inaccessible.