She throws this ball made of iron quite high into the air. Unfortunately it goes offscreen and I can't for the life of me get a measurable angle where it doesn't do that so I'm going to add the distance onscreen to the height of the ball to get an approximation of how far she threw it.
If you have any questions regarding how I got the values in the images don't hesitate to ask. But I will say Naraku is canonically 4'11"
So first I will determine the weight of the ball which is composed of iron. Oh and since I know someone's going to bring it up, there's no reason to assume this thing is hollow. It's meant to be a weapon so I'd actually say the opposite is likely the more accurate assumption. V = 4/3*pi*r^3
The radius is 168.257142857 cm
4/3*pi*(168.257142857^3) = 19953043.03 cm^3
Mass = Volume*Density, the density of iron is 7.86 g/cm^3
19953043.03 x 7.86 = 156830918.216 g or 1.56830918216x10^5 kg or Class K
To find how high she threw it, like I said earlier, I'll add the onscreen height to the height of the ball.
271 + 634 = 905px
905/271 = 3.33948339483
3.33948339483 x 336.514285714 = 1123.78386926 cm or 11.2378386926 m
It takes the ball 25 frames to leave the screen in the second clip and the video runs at 30 fps so in 0.83333333333 seconds, this ball weighing 1.56830918216x10^5 kg traveled 11.2378386926 meters.
Acceleration = 2*Distance/Time^2
(2*11.2378386926)/(0.83333333333^2) = 32.3649754354 m/s^2
So finally we take Acceleration*Mass to get the force in newtons then convert to kilograms of force
32.3649754354 x 156830.918216 = 5075828.81557 N or 5.175904937547799x10^5 kg or still Class K