Actually, both balls are identical to each other, and have no special allegiance towards any player. The idea is that if the balls are left to bounce around unchecked (and they are pretty bouncy, gaining momentum from each rebound) they are a dangerous hazard that might destroy you, your opponent or both. It'll be random.
But they can be grabbed (no istagib) and then thrown in the general direction of your opponent. Making them weapons in that sense.
And finally, I figure in a grav-less, you could find yourself floating just out of reach from the sided of the drum. So unable to move. but since these balls tend to get around, it should be possible to use them for a push to the walls or a better position.