Yes, I am familiar with the average strength of a human. On Earth. Where I know what gravity is, and can do the math for it. Where I know what our evolved muscle density is. So yeah, it's not something I can just assume. And that sword...

[He gestures at it even though clearly Sephiroth knows what David means.]

There are things in my world that will cut through a car like butter without a lot of strength behind them. Adamantium and Vibranium come to mind. So some of what you did could be strength, and some could be the sword.