What weapon is capable of this?

For me it's less "hurf durf America actually won!" and more annoyance when retards fail to understand the method of defeat and draw a dangerously incorrect conclusion. The NVA won by outlasting American public opinion and avoiding a direct fight as often as possible, which they ironically achieved with the failed Tet Offensive (the NVA being able to launch such a massive attack ran counter to the Johnson administration's narrative that the war was nearly over and the NVA was on its last legs). Meanwhile retards on the internet have somehow boiled this down to "hurf durf America was defeated by rice farmers with sticks!" and proceed to delude themselves that they could take America in a straight fight, which ignores the crushing casualties the NVA took in direct engagements (not to mention the mass destruction inflicted upon the civilians and the land itself).
In this way the K/D matters, not because it magically lets you turn a defeat into victory, but because it shows there's a high price to pay to win against America, and you have to be willing to pay that price. Unfortunately, retards ignore that price (as they massively downplay America's capabilities), and then proceed to start fights that will cost them far more than they could have possibly gained. For the Vietnamese the cost was worth it, as they not only reunified their country, but they also retained enough strength to ward off other outside powers (China). For those who followed, most of them didn't even gain anything at all (Noriega, Saddam, the Serbs, hell I would even argue that the Taliban also gained nothing since they seem to be worse off than before the invasion despite regaining control of the government).

Plus I simply just find it disrespectful to reduce Vietnam to farmers with sticks. Those guys were running some of the most advanced air defense networks in the world at the time, they deserve more credit than being reduced to primitives just to disparage America.

the amusing thing for me is all the retarded foreigners that refer to the vietnam war as an american invasion

Probably some bizzaro version of Kaiserreich

Earlier EU under German leadership, and probably, by the modern day, would be an actual country rather than a federation. Prior to WW1, Austria was actually doing a pretty good job integrating its Slavic populations (not assimilating; rather, giving them equal rights, providing government services in local languages, etc) and Hungary would have eventually followed suit. Remember that "Srbe na vrbe" comes from a Slovene poet in Austria-Hungary calling for the genocide of serbs; Austria-Hungary did not break apart in some sort of frenzy of nationalist revolutions; minorities in WW1 fought bravely for the Kaiser and the King, and Austria-Hungary had to be dismembered by treaty.

Germany and Austria-Hungary were increasingly tightly economically integrated. This would have naturally evolved into something EU-like; first economic ties, then more standardization, common currency, shared regulatory bodies, etc. With their territorial gains in the east they would account for over half the population of Europe, and Poland, Ukraine, Belarus, etc, would have seen rapid industrialization and booms in infrastructure (most of Germany's railways today date back to the Imperial era) together with education improvements for the locals (Germany was fastidious about education; Kenyan children in German Kenya had better literacy rates than British children in the UK). Smaller neighbours like the Netherlands and the Nordic countries would naturally fall into their orbit and be integrated, etc. France might eventually decide to get over themselves and get in on the federation, or its expansion might stop there and be focused more on the Balkans and Eastern Europe. Either way it would be one of the world's top powers.

The USSR would be a threat, but if it tried anything it would get its shit kicked in pretty hard since Mitteleuropa would be able to focus directly on hammering them into oblivion rather than dealing with a two-front war plus blockades the way Nazi Germany did.