a player can see ones number; but only if the player you are seeking is facing sideways or in front of you (in the screens perspective). If they're looking at your back, it's a bit hard to tell who it is, considering the monotonous haircuts and the cloaks from the Middle Ages
Agreeably this is common sense. But pkers are not good roleplayers, so they won't even face who they snipe, and with their back to their victim they can log off without having their number seen.
I doubt there will ever be a way of hiding your number.
How about adding a number, based on height, weigh, age, which can be used in game, which can be concealed, and the numbers we have now are for entirely ooc use, like identifying a pker. That is the only way I see of reasonably roleplaying around the problem.