PantsForSquares

That... actually explains a lot. I thought it was because he didn't want others to have Awakened steel, but it makes sense for Vasher to be aware of the danger that something like Nightblood poses in the long (long, long, long) term

The primary reason I came up with the conclusion that Honorblades are Splinters is as follows: First, we know that the nine major spren types and the greatspren created the Nahel bond in imitation of what the Honorblades do. Second, spren are known to be fragments of Honor's, Cultivation's, Odium's, or even Adonalsium's (although this is uncommon) power. Some such spren, such as honorspren, are Splinters of these. I figured that only certain Splinters were compatible for the purpose of Nahel bonding, explaining why there are only 9 types of Nahel spren. Since the Nahel bond was made in imitation of the Honorblades, it stands to reason that there is some manner of structural similarity between Honorblades and spren. The largest similarity that comes to mind is that Honorblades are Splinters. I concluded that Honorblades intentionally were made with a heavily limited Cognitive aspect in order to prevent the formation of an Intent. Whether this is a drawback of Tanavast designing them to be usable by anyone remains to be seen, but it would explain an Honorblade's inability to change shape like a living Shardblade (and we know that the Honorblades aren't dead spren). Again, the biggest gap in my theory comes from a lack of understanding as to how Splinters work. We have four or five examples, depending on how valid this theory is (Seons, Skaze, spren, Divine Breaths, (maybe) Honorblades). Beyond that, I can only make conjecture based upon observations, like how spren have their Cognitive aspects reduced when they travel to the Physical Realm, for instance. If the Heralds have the Cognitive aspect that would have normally gone into the Honorblades, that could account for the Blades' lack of Intent. There also has to be some rationale behind the Heralds' agelessness, at any rate.

That almost makes it sound like Nightblood is the Cosmere's equivalence to the Second Law of Thermodynamics. That Investiture has to go somewhere, but it's not like other forms of Investiture, where it still remains usable after being absorbed by Nightblood. Good job, Shashara, you kicked off the Investiture Death of the Cosmere.

I'm using bond out of consistency, actually. It's clear that there's some sort of link between the Honorblades and their users that are formed upon wielding them. I'm using "bond" because the term is used across the board. Fabrials require a bound spren; Listeners bind spren to themselves to change forms; Shardblades are bound (though we now know that they're just dead spren simulating a small part of the Nahel bond), and there are the Nahel bonds that can be made between spren and people. This "bond" that is forged between an Honorblade and its user isn't the Nahel bond - that much should be fairly obvious. However, in order for the spren to create a derivative of it (the Nahel bond), there has to be some degree of similarity between the two. But, after further consideration, the word "bond" is more than appropriate. I should probably call it something else to avoid confusion with the Nahel or Listener bonding methods. Honorbond, perhaps? I'm of the opinion that the Divine Breath is what creates a Returned's body, as we know that they essentially look however they imagined themselves to be before they died. In essence, it acts as a tether between the Cognitive shadow of a dead person, and the Physical Realm, in addition to granting the Fifth Heightening*. Along the Splinter design parameters I mentioned above, it seems like the Divine Breath is heavily Physical (supplying a Physical form, and providing the ability to heal any wound, at the cost of the DB) and and somewhat Spiritual, in the manner that all Breaths are. I'm not sure where they lie Cognitively, as they do seem to have some minor form of Intent (enough to nudge the Returned along Endowment's own plans), but it seems that it isn't significant enough - and that's where the Cognitive shadow comes in. *If Heightening is linked to the total magnitude of the Breaths possessed by a person, and not their number of Breaths, then a single Divine Breath, with all of its Investiture, would probably contribute far more than one normal Breath. Anyways, my point is that it should be fairly obvious, given the difference between the spren/seons/skaze, and the DB, that Shards can intentionally design their Splinters. The two types of Splinters that we have observed that come from a living Shard (Splinters and Divine Breaths) are unique in that regard. There are only nine types of spren (excluding greatspren) that can form the Nahel bond, and there are unique spren that can bond with Bondsmiths, for instance. This is part of the reasoning behind the idea that Honorblades are Splinters of Honor. The other part of the logic results from the following question: What similarities exist between the spren and the Honorblades that allow them both to grant Surgebinding? We know that That's because Wyndle has to meet Lift "part of the way": He doesn't exhibit the full-fledged memory loss that Syl and Pattern have - he even remembers what his job was, for instance, and how Investiture works. With all other Surgebinders - Ym, Shallan, Kaladin - their spren all seem to display a startling lack of mental capabilities upon initially being bound - especially compared to Lift and Wyndle. The only significant difference between Lift and the other Surgebinders is her rather odd state of existence in the Cognitive Realm, due to her request with the Nightwatcher.\

In that case, an Elantrian might not be able to use Nightblood, but someone using ChayShan might, especially if the style has a form for swordsmanship. It might not be as strong as using Nightblood on Roshar or even Nalthis, but it's quite possibly doable on Sel. Then I suppose that using anything but a copper metalmind with Nightblood is just as effective, then.

I was actually curious if Nightblood would just drain the stored Investiture, without any need for tapping on the part of the Ferring in question.

It would eventually drain the Dor, but that's only a problem if Nightblood was left unsheathed 24/7 (or whatever the equivalent is on Sel). Regardless, it would be like trying to drain all the Stormlight in Roshar by following the highstorm around the planet, but considerably more difficult. Remember, the Dor lacks the same "release valves" that Rosharan Investiture has, and so, there's probably a lot more of it pent up, waiting to be spent.

We need to leave Nightblood in the hands of a Nicrosil Ferring one day, just to see what happens. Bonus points if they're a Nicrosil Compounder. But here's the thing: People on Roshar don't have Breath, or even an analogue to it. Stormlight can be collected, but only Surgebinders have shown the capability to store Stormlight without the aid of gems. Nightblood would run on the Stormlight stored in the person, then presumably start absorbing it nearby infused gems, and finally drain the "spark of life."

It makes sense for it to be Hoid. He is definitely a "wanderer," and the Diagram was written by the smartest individual on Roshar at the time - a glance and understanding of what Hoid can do would quite possibly reveal the existence of the Cosmere.

*gasp* I knew it! But that only makes me wonder: what snack corresponds to Odium? Froyo?

I'm more using "bond" in the sense that there's some sort of link that's formed when a person wields an Honorblade. It's not the Nahel bond, that's a given, but there has to be a link of some kind that provides access to the Surges in the first place. I went with "bond" because it's using existing terminology, but I can change it to something less confusing. Think of an Honorblade's bond as being a universal attachment to someone's Spiritweb (at the cost of not being permanent), whereas a Nahel bond requires Spiritweb damage to create a more permanent bond (so long as the Intent of the spren is adhered to). As for your second point, the idea that Splinters need to be self-aware comes from observation of the Seons and Skaze of Sel, and the spren of Roshar. However, we also have another example of Splinters that are not self-aware - at least, not in the sense that we perceive it: Divine Breaths. These allow the Returned to, well, return to Nalthis, but require the consumption of Breaths in order to sustain themselves. Honorblades, as far as my best guess goes, functions in much the same way: They provide Surgebinding to anyone who can use them, at the expense of an increased cost of Stormlight. One of the potential speculations that I left out here is the possibility that self-aware Splinters (like spren) can exchange their presence (I want to say Connection, but I'm not sure if that's entirely correct) between the Physical, Cognitive and Spiritual Realms. This results in things like memory loss for spren*, for example. However, Honorblades, which are - under this framework - explicitly created to be highly Spiritual (to easily grant Surgebinding) and somewhat Physical (because they have physical forms), come with a greatly diminished Cognitive aspect. As such, they lack the awareness to alter their own capabilities. Dead Nahel spren are sort of a sad exception to this, with no Physical presence beyond their Shardblade, and no apparent Cognitive presence beyond the sheer shock of having the Nahel bond be suddenly severed. *Wyndle is a special case: Since Lift partially exists in the Cognitive Realm, this should allow Wyndle to bond to her without sacrificing his Cognitive presence.

So, yesterday night, during a particularly interesting moment of clarity brought on by a lack of sleep and energy drinks, I finally stumbled on what I consider to be my biggest theory related to the Cosmere as a whole. That is, I have a pretty solid idea on how Honorblades function. So, let's get down to business, and take a look at the facts that we know. We know that spren (but only certain types) are able to imitate what the Honorblades are capable of. We know that most of the spren are made from either Honor, Cultivation, or both (I'm not including Voidspren here). There are even some pre-Shattering ones hanging about. We know that some spren, like the honorspren, are actually Splinters of Honor (Syl is a "little piece," I believe the term is). Similarly, there are other spren who either Splinters of Honor, Splinters of Cultivation, or quite possibly both. Splinters are primarily things of the Spiritual and Cognitive Realms, and not so much Physical. (Source) We know, from Warbreaker, that Splinters can be made from living Shards of their own free will. Odium just likes Splintering Shards so that he doesn't absorb them, and so it's immensely difficult for others to seize that power. So, with these facts assembled, I'd like to make the following proposition: Honorblades are Splinters of Honor. Simply put, the honorspren (as an example) were able to mimic what the Honorblades did in the form of the Nahel bond. If that is the case, then there must be some similarity between them (ie, Jezrien's blade and an honorspren would both bond to someone's Spiritweb in the same place). However, there are some key differences, and that's where things get interesting. From what I can gather, the Honorblades lack any form of Intent, or their Intent is not particularly relevant. This is presumably designed by Tanavast, as the Honorblades are capable of bonding to any individual and granting them access to Surgebinding. The spren, on the other hand, can use their bonded individual's alignment with their Intent (ie, adherence to their Words) in order to greatly increase the efficiency with which Investiture is processed and controlled. So, in exchange for being available for virtually anyone to use, the Honorblades lack the ability to process Stormlight as effectively as a Radiant who is fully attuned with their spren's Intent. I've got some further speculations, but these are mostly rough ideas, and heavily rely upon further understanding of the Spiritweb and the Spiritual Realm. Since these aren't subjects we fully understand yet, it's something I'll reserve for a later date.

So, I'm PantsForSquares (PFS?), and I've been a long-time fan of Mr. Sanderson's books. I usually lurk these forums, but never really joined up. I recently posted a theory on Reddit that hasn't really been brought up, and I'd like to share it with you guys, and maybe join in on the theory fun.