The analogy of a weight spinning on a string does not apply to a spinning rotor blade as the effects of gravity would be nil compared to the centrifugal forces involved. If on the Moon the mass of the blade would be the same but the effects of gravity, which is much less, would make it much easier to pick the blade up. However if you had the means to spin that blade up and rotate it at 250 rpm the centrifugal loading would be the same as that on earth.
On earth when the blades are being spun up the blades will assume a radial position and extend straight out from their attachment point on the rotorhead. They would also hang back from the radial line due to their inertia. Whether this same inertial effect would occur on the moon I couldn’t say because the math involved is way beyond my understanding.
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The Cat