The real point where simulationism is lost in D&D is that you can hit someone in the face with a battleaxe three times, and they don't die.
If my players are attacked by a battle axe attack 3 times... I have them
describe how luck and desparate last second skill and the various factors incorporated in hit points (read the definititon of hitpoints from version 1 through 4 for ideas) reduce and minimize those attacks...
The neat part of letting the player describe this part is you get to involve them out of turn (some players ask me to do it... others love having defensive narrative permission - I only rarely have to adjust there description)
In real life, it is possible to disarm an opponent, but it's a great deal harder than just killing them. You can't say that it's unrealistic to forbid people to try disarming enemies, because the whole hitpoints system is an obstraction to start with. It's the reason disarming and sundering was so powerful in previous editions - because effects that can disable an opponent by means other than reducing them to 0 hitpoints are way more effective.
Mechanics which semi permanently nerf somebody who arent nearly out of luck is not a good idea or a good simulation and never was.
Basically the house rule using zero hit points in the permanent disarm are using something quite like an extension of intimidate rule (and very likely with its flaws removed.)
Instead of tying it to a too easily front-loaded/over-optimized skill it is tied to a normal attack and instead of using the bloodied threshold it is tied to being within reach of being out of the battle by a single attack. (those maybe very close to the same point )
The intimidation mechanics limitation of your target being bloodied is nearly mechanically the same as being within one heroic attack of being defeated. (but maybe only for enemies of the same level and there are important exceptions). And those exceptions are good reasons to use an attack for the disarm check and use the zero hit points threshold.
Presentation is all the difference.
So the jackie chan pacifist pc describes his attacks as him defending himself in way that humiliate and exhaust his enemies turning there attacks against him in to attacks against there allies and themself etc all working at exhausting his enemies when the dm describes them like they are frazzled tired or seriously confused he makes an attack and describes it as a form of disarming if it works and causes sufficient hitpoint loss they lose there weapon... if it fails they dont lose there weapon but next round another such attack is very likely to work and his enemies are likely demoralized and afraid so at disarmed zero hitpoints they run away.. or he might have had there weapon bounce back from one of there attacks and clonk them in the head and they just fall unconcious. If the player suspects npcs as being minions (for instance the described exhausting defensive attack against one results in the target knocking themself out) he changes a bit and describes a nice flamboyant disarm even though the next one doesnt already seem bloodied aka ready for disarming... and sure enough the minions weapon gets stuck in the cieling...
ummm hell yeah we can do disarms with 4e rules...
