I'd have to say your interpretation of 0HP is a little off.
Your class comparison list is ridiculous, since those are all classes D&D has always had. There has always been a fighter class. Just because WoW has a warrior class doesn't mean D&D somehow copied WoW by having the fighter class its always had in its new edition, nor wizard, cleric, paladin, ranger...
PCs are special. Monsters are done at 0 HP.
Which means it isn't suitable for modeling those all-to-common and very cinematic fights in which disarming is not the end of the fight.
It was way too easy, disarming someone in real life is VERY not easy, it requires perfect timing, the right amount of strength and leverage and the opponent to give you an opening...<snip>...
No it should require an experienced warrior (level 16 for example?) and be something he only rarely gets the perfect chance to do (like... once per encounter perhaps?).
The problem I see there is that it covers actions that you can't do with existing powers. But in this case there is an existing power. Should we really let players parrot powers using DMG42?
first you need to grab the opponents weapon
Grab (or grab opponent's weapon): standard action, strength vs reflex, no weapon bonus