How big is Cloud's sword

[Newmani]

The sword weights somewhere between 120-240lbs, depending on how thick you think it is. (1"-2").

And also assuming that steel has the same density in the world of FF7.

I dunno if it weighs THAT much. There are a lot of lightweight alloys out there, and whatever the heck it's made of it couldn't be too heavy because if it was 240 pounds Cloud would have a hard time even lifting it up. I say it weighs around 50 lbs, maybe 70. Maybe lighter, because it's clearly sharp enough to slice through steel and concrete like a butter knife, so it's unlike any steel alloy we have here.