A Windspren

Yes, and if they are being pushed backward that much, the effect on the Blade will be negligible

And if the Shardbearer keeps a hold of his weapon, the Coinshot flies back into a wall and dies. The Nicroburst, Pewterarm and Leecher then get cut in half by a 6 ft long Shardblade.

I think you're overestimating the power of Pewterarms. Mistings in Era 2 are much less powerful than Era 1 Mistings, and even if they were as powerful, what would they do against Shardplate? A sword wouldn't do much even if they put all of their strength behind it, because it would either be chopped in half or shatter against the armor. There's also the fact that a Pewterarm would have to get in range of a 6-foot long Shardblade if they wanted to do more than make faces at the Shardbearer. If they tried using their own 6-foot swords, they would be immediately chopped in two by the Shardbearer.

Roshar could do a similar thing with fabrials. A squad dedicated to protecting a Shardbearer would have a Repeller fabrial to push away any projectiles that were fired at the Shardbearer, one of those fabrials that can drain/add Stormlight (I forget what they're called, but Hatham used them to make his rings glow only faintly) could be used to refill Shardplate if it gets drained, and a team of archers with glass arrows would kill any Mistings before they could get close to the Shardbearer. Mistings would be detected using Warner fabrials. In any case, the Shardbearer would likely kill the Shardkillers before they even got close to him. If Mistings were to try and push on Shardblades, even with a nicrosil boost, it would only affect the Shardblade a tiny bit, and the strength of Shardplate would help the Shardbearer keep his grip on it. Also, the Sharkillers would have to refill on metals in the middle of a battle. As a response to the earlier discussion about whether or not Rosharans could reverse-engineer guns and if Scadrians could make fabrials: It's easy to take apart a gun and see how it works. It would probably take a few months for Navani to have a working gun ready. Fabrials are a different story. If you take apart a fabrial, you get a bunch of metal wire and a glowing gemstone. The Scadrians would have no idea how to build more, as the inner workings of fabrials are barely known even to artifabrians. If someone from Scadrial were to defect to the Roshar side, they would likely be a normal citizen or soldier. Everyone on Scadrial could tell you the basic principal of how guns work, but if a Rosharan were to defect, they would likely be a slave or darkeye. The only ones who know how fabrials work are ardents and artifabrians, and there's not many slaves or unhappy darkeyes among those. It's far more likely that Roshar would develop guns before Scadrial develops fabrials.

Yes, but remember that Shardbearers are extremely heavy due to their Shardplate. The Coinshot or Lurcher would be pushed/pulled, instead of the Shards.

If we're going by the current era, remember that Scadrial has no army, and if they were to train 100k troops really quickly to invade a place no one has even heard of, people would start to get suspicious. Plus, there's the problem of Worldhopping that many people, the support infrastructure needed for an army, and constant food shipments to Roshar. Once they end up on Roshar, they either end up in the Purelake (lucky) or the Horneater Peaks (unlucky), and according to Rock, the Shardpool there kills all humans. All of those soldiers are also without nearly any training, like the troops in Kaladin's old army.

There was a WoB that Sazed cured all diseases on Scadrial. It didn't say that he made the humans immune, but that he removed them.

For point 2: Sazed cured all diseases after his Ascension to give humanity on Scadrial a better chance at surviving.

Yeah, he might not want to make more, but if the Command given to the Awakened swords was more specific, so that it wouldn't harm people unless it's protecting, Vasher might be convinced to make another Nightblood. If we're going to consider the willingness of both sides to fight, I doubt that everyone in Elendel would want to worldhop to a faraway planet to fight a pointless war.

I think we have a WoB that Vasher knows how to make more Nightbloods. He has an abundant source of Investiture in the form of Stormlight, and has already figured out how to use it to keep him alive. He would just need to find a way to Awaken with it, but he will probably be able to do this by the time of Era 2. We need a "Team Roshar" and a "Team Scadrial"

I think that a perpetual Highstorm would completely destroy the Scadrian army, if the Stormfather felt like helping out. Plus, Vasher is on Roshar, so he could create hundreds more Nightbloods, but with more specific Commands like "Protect Roshar."

I'm pretty sure that Nightblood would defeat someone with the Bands, as we have a WoB that they're less Invested than a dead Shardblade, and Nightblood is orders of magnitude above those.

I just had a thought: Since Radiantspren, such as Pattern, can manipulate objects such as locks, what's preventing spren from triggering all of the Scadrian army's guns to go off while they're pointed at each other? Furthermore, since the Stormfather can control Highstorms, he could just create an endless Highstorm right on top of the Scadrians. Gunpowder, and even guns, would be ruined, along with any electronics.

When I said "full might of both worlds," I meant if both armies had access to all the powers that ever existed on their world. I'm pretty sure that an army of TLRs never existed on Scadrial. But, if you want to play it that way, then what if every soldier on Roshar has all 10 Surges (which probably doesn't help much against your army of TLRs), every spren has the might of the Stormfather, every Listener is in their most powerful form, and if you want to bring Shards into it (which is kind of unfair for both sides, as they could just rip the planet in half), Roshar has both Cultivation and Honor, which aren't opposing forces. Sazed couldn't use the full force of his power, as his Shards are opposites and make it hard for him to act.

Which is exactly my point. There is a scenario where both worlds have all that is or ever has been avaliable to them, and one where the war happens at the time of Scadrial Era 2. My assumptions about Roshar at the time of Era 2 are pretty reasonable. As for your comment about complex mechanics, just look at the elevator system in the Palanaeum, or Dalinar's mechanical bridges. Also, Mistborn Era 2 is 10-20 years after the end of Stormlight 5, so I assume that there's a lot of time to rebuild, especially with the help of Soulcasters. I haven't invented any fabrials either, besides the Repellers, but it's reasonable to assume that if you can reverse conjoined fabrials simply by changing the gemstone type, artifabrians will figure out how to reverse Attractors by Era 2.

How am I skewing the terms?

My assumption about the Heralds was for the first scenario, where the full might of both worlds is brought to war. In one of the quotes from Words of Radiance (the in-world book) there's a statement about several thousand Radiants in a single battle.

Most of you assume that Scadrial would get the benfits of Hemalurgy, Koloss armies, Southern Scadrian magic, and other advantages that most people on Scadrial have no clue even exist. Now, we can either make this war so that the full might of Roshar and Scadrial fight each other, or it can be current Roshar and current Scadrial. With the full might of both Shardworlds, it would be a tough war. Assuming that the entire Scadrian army can worldhop, they would likely end up either on the Horneater Peaks or the Purelake (if the rumors of a Shardpool in the center are true). If they started at the Horneater Peaks, they would be stuck there because of the extreme cold and would likely die without a ton of heat Medallions. If they came out in the Purelake, it would be much easier for them, but their guns and other metal technology would rust, slowing down their expansion. Scadrial would lose almost all battles due to the Radiants and Heralds crushing the Scadrian lines, but Scadrial might be able to win a few by attacking in multiple places at once. However, even the full might of Scadrial would not be able to hold up against thousands of Radiants plus the Heralds. If a TLR Mk II showed up, the KR would have a hard time dealing with him, but the Heralds would be able to take him down after an extended fight. If that failed, Nightblood, since it's on Roshar, would utterly destroy TLR Mk II. Scadrial would be crushed in this scenario. If the war is with the current era, remember that Mistborn Era 2 takes place after the first five books in SA. By then, there will probably be several dozen Radiants, plus their squires, and a few Heralds might snap out of their insanity. A lot of the advantages people attribute to the Scadrians are railroads and telegraphs, but it takes a lot of work to get these set up. In WWI and WWII, invading armies would take advantage of already existing infrastructure. If Scadrial was invading Alethkar, there would be no existing infrastructure for those technologies, and it would take far too long to set up new ones. Scadrial only has the advantages of guns and Allomancers/Feruchemists. Roshar would lose the first few battles, due to the Scadrian's guns, but Rosharan scholars seem to know a lot about physics. They know that sounds is a wave, have a pretty good understanding of the laws of motion, and even are pretty good chemists (the medicines that Lirin uses are made with pretty advanced extraction methods). They wouldn't take long to make rudimentary guns, especially with ones scavenged from Scadrian corpses to study. After the first few battles, Roshar would be narrowly winning. A lot of people make the point that the darkeyes would revolt and join the Scadrians, but at the end of WoR, there are already riots in Kholinar, so by the end of book 5, there will probably already be a lot of reform in the Vorin social structure. The lighteyes could also just say that the Scadrians are Voidbringers or something, and that their invasion is a Desolation. Also, with current fabrial technology, the Alethi could build viable hovercraft by using Navani's archer platform, but by stacking the counterweight on top of the floating platform. Add a pressure fabrial, and you can fly over the Scadrial army and drop glass shards, or even Shardblades, on them. A metal Repeller fabrial would keep any bullets away. Fabrials can duplicate all the powers of Allomancy, as we've seen fabrials that can affect emotions, sensations, warn of nearby Investiture (I assume that the Warning fabrials work by detecting the inherent Investiture in humans), push or pull objects (and not just metal!), increase strength (Shardplate also does this, but it is more limited) and they can even affect objects and people that don't have inherent powers. Scadrial is limited by the amount of Allomancers or Feruchemists it has, but fabrials can do a lot for the Rosharan army, and work for anyone. Scadrial would have a hard time learning about fabrials, as all research would have to be on Roshar, because spren only appear in the Physical Realm on Roshar. Even then, it would be really hard to discover how to trap spren in fabrials. By the time they discovered how to make basic fabrials (not the advanced ones that Navani has), the war would already be over. Public support for Scadrial's invasion would decline rapidly, and the Alethi would win after a few years.

I think that there isn't really much special with aluminum. It might just have to do with how a specific magic system works, and I doubt that it is a universal Investiture negating metal.

I don't think that aluminum could block a Shardblade, as Shallan gets an aluminum necklace as a present, and people would probably notice that it would block Shardblades.

I think it's because the 11th lamp on the city-based Oathgates messes with how they work Jasnah couldn't repair the one in Alethkar because she didn't know what they were supposed to look like, but now that Shallan knows that there isn't supposed to be an 11th lamp, she can send a message by spanreed to, say, Kaladin while he's in Kholinar, and he can start transporting people from Kholinar to other cities.

Maybe the hair is from Nalthis? Royal Locks, anyone? I'm also guessing that the sand is from that one unreleased book (can't remember the name) that takes place on a sandy world, where Autonomy/Bavadin is Invested.

Maybe he can if he actually tries, because he believes he can on a Cognitive level?

Oh wow... That... Actually makes sense... Kinda.

Maybe the weapon was the 16 Shardholders, before they got Shards? I mean, the WoB doesn't say that the weapon was destroyed, just that it no longer exists in its original form.