Like quite a few others on the 17S Discord Server, I had one major nagging question after the SDCC Reading. How does the fabrial we see work? While it's effects are somewhat clearly shown, the method behind it is very important to understanding the weapon, and to understand the nature of the arms-race that is apparently going to be an essential part of Rhythm of War. Although this theory definitely does have holes, I think it's a fairly elegant solution, though it's definitely not perfect.
To start let me lay out the basic groundwork my theory builds on. Maybe I'm wrong about this, since I can't find the reading on Arcanum yet, but I remember Syl saying something along the lines of 'I felt faded, distant' when Kaladin asked her about the effects of the fabrial. Despite it's ability to block Radiants from surgebinding, the Fused seems to find no issue. Lift, notably, is also affected by the aura of the machine. Finally, Kaladin is still able to hold Stormlight, but not use it.
My theory is essentially this: The fabrial somehow pushes the Realms apart, weakening the Physical presence of Spren, and weakening Radiants ability to access the Nahel bond. This theory seems at first a simple, clean answer, that makes at least some Realmatic sense (to my admittedly weak understanding of Realmatics). It also, to me at least, seems to line up that if a Perpendicularity can pull the Realms closer, an 'anti-Perpendicularity' can push them apart. When the Realms are pushed apart like this, a Spren has to reach 'further' to give the Radiant the benefits of their bond, thuse causing the weakening, or in the specific case we saw, elimination of the powers given by that bond.
The information we have does make it somewhat difficult to come to such a simple conclusion, due especially to the apparent specialized nature of the fabrial, in blocking Radiants but not Fused. Indeed, at first, this seemed to be the end of the road for my theory when I discussed it briefly on Discord. However, there is a simple work-around that makes a decent amount of sense.
You can't stretch a bond when the Spren is wholely in the Physical Realm. So, a second claim is necessary to make this theory work. Singer bonds bring the spren wholely and irreversably (unless released) into the Physical. There's no apparant reason, from what I've seen, that this would be implausible, and it would make for interesting implications for the future of the war: fabrials that can be used as weapons would be the only counter to the 'anti-Perpendicularity', and thus, we have out arms-race, since fabrials, like Singers, trap Spren in gemstones. Radiants, on the other hand, strengthen their bond with each Oath, and the Fifth Ideal, the way I see it, likely brings the Spren into the Physical Realm.
To conclude, based on the information in the Sand Diego Comic Con reading, it seems logical to me to say that the fabrial we see used by the singers pushes the three Realms apart, and makes things like the Nahel bond, which operate through multiple Realms, substantially weaker. However, a Spren trapped in a gemstone, like in the case of Singer bonds, or another fabrial, is wholly in the Physical, and so cannot be pulled apart from their host the same way. Radiants who have sworn their Fifth Oath, giving their Spren total access to the Physical realm, and full Physical manifestation, would likely similarly be unaffected by a fabrial like this, or at the least affected substantially less.
I'd love to hear back from some of you awesome Sharders out there with feedback, refutations, or just critiques of my theory. I'm sorry I don't have a lot of textual evidence for this, but I don't have a transcription of the reading, and I don't have time to look back into the books or rewatch the video for references at this time.