There's barely any difference in weight. Also, even the huge "zweihanders", claymores and such weren't that heavy. Like 2kgs max. People make a big deal out of the weight, despite the fact that you were expected to be slashing the air with it for a very long time - standing in a doorway for instance. What the difference is - is the existence of the crossguard. German / italian longsword uses them extensively. Katanas almost don't have it.
The interesting thing is polearms though. Japanese naginata masters adore the halberd for instance. You can use most of the techniques you already know, plus the added utility of hooking someone's leg, and the spike at the end.
I think most of the differences are to either take advantage (make it cover more incoming strikes) or accommodate (keep it from poking you in the head) the cross guard.
it'd be hard to realistically compare them because both styles were designed due to different circumstances. Western sword styles were designed to combat heavily armored units, so they tend to favor power, while due to the lack and poor quality of japanese steel/armor, japanese sword styles favored quick strikes as targets were more often than not, lightly armored, so it's a question that if you willingly chose to put the fighting styles against each other, whether or not the competition is lightly armored or heavy armored basically affect whose more likely to win the match.
Look, I just want to see the two styles fight. Balance issues and the context of why one style will be more effective are beyond any immediate concern. Let's see some fucking moves.
Western styles weren't meant to combat heavily armored units. You aren't getting through heavy armor with a sword. Unless you use it as a mace (mordhau) or use it as a dagger by half-swording(grabbing the middle of your blade to act more like a dagger) and getting through the squishy bits. At which point, why not use an actual dagger. Also, there are loads of manuals talking about fighting unarmored opponents while you are also not wearing armour.
It’s interesting because Star Wars saber battles were very clearly inspired by Samurai duels, yet if you asked me which one looks like a Jedi holding a lightsaber I would point to all the pictures of the European swordsman.
Inspired doesn't mean much. "Jedi" fighting is useless and made to look cool in extended duels. No actual techniques from historical martial arts are being used
Depends on what you mean by standard italian. Most people study Fiore, with his flower of battle book. And it's anything but "standard", it's full of tricks and "dirty" plays. Like Liechtenauer / Meyer would be the "default", and Fiore being the "krav maga" version.
German school of fencing has a bunch "master strokes", like the zverchhau, krumphau etc. But italian has all of that and so much more