Say what? Player 2 attacker? Explain it again heh :D
I don't get the question.
You mean, how the player 2 can get the target of player 1 who is the attacker?
If that's the case, then.. Well, by default when someone attacks you, you get his target, but anyway. Something like this.
final L2PcInstance targetPlayer = (L2PcInstance) getActingPlayer().getTarget();
if (targetPlayer != null)
targetPlayer.setTarget(getActingPlayer());