Just do whatever change you need clientside. Then it only affects the current player.
Simple example:
PHP Code:
// display block.png unless you have clientr.boo set;
// if it _is_ set, then, display bcalarmclock.png instead
//#CLIENTSIDE
function onPlayerEnters() {
if (player.clientr.boo) {
this.setImg("bcalarmclock.png");
} else {
this.setImg("block.png");
}
}
You do the same thing for characters, substituting the various body parts for the setImg. You can change the check to check if, for example, a player has a weapon.