The Eight Cue Balls

Here is another interesting puzzle.
The answer, rot13'd to prevent sneak peeking, is below.

I give you 8 cue balls, identical in appearance, and a scale.
Of these 8 cue balls, one is slightly heavier than the other 7, but not enough for you to notice when you hold it.
The scale can only tell you that it's balanced, or if it's not balanced, which side of the scale is heavier.
You can use the scale 2 (that's two) times. How do you find out which is the heavier cue ball?

Boivbhfyl, fgnegvat jvgu sbhe phr onyyf ba rnpu fvqr bs gur fpnyr jvyy trg lbh abjurer, orpnhfr lbh jvyy unir gb jrvtu guerr gvzrf.

Gur gevpx vf gung vs lbh jrvtu phr onyyf jvgu gur fpnyr, lbh nyfb tnva vasbezngvba nobhg gur onyyf lbh ner ABG jrvtuvat.

Urer'f ubj lbh qb vg.
Chg guerr phr onyyf ba rnpu fvqr bs gur fpnyr, yrnir gjb ba gur gnoyr.

Vs gurl ner onynaprq, jrvtu gur gjb erznvavat barf. Juvpurire vf fubja nf urnivre vf gur phr onyy lbh'er ybbxvat sbe.

To decode, use the rot13 converter.