So are you saying that "creativity" is defined as figuring how to take advantage of a game systems mechanical defects (bag of rats comes to mind)? Funny, I always thought that's what a DM was for and judicious use of the word "No". And don't get me wrong...I'm in favor of the "say yes" concept, but there are times where you are required to "just say no". For example we have a running joke in my group.....the first level PC's ask if they can have an "Axe of the Dwarvish Lords"...and I just say "No".
It's not a mechanical defect that pushing someone off a cliff takes them out of the battle. It's not a mechanical defect - it's a real, in-game decisive moment. These things happen; it's not a flaw, it's a part of the game's reality. If it's
possible in the game, and it's a battle winner, it'd be
absurd for a creature not to do it!
The solution cannot be to turn the game into a farce. Whatever solution you come up with should be consistent and reasonable in-game.
For example, you might rule that dominate is a sort of mental confusion; the affected loses track of goals and can use only the most common, habitual actions - and in combat, unless the affected habitually throws his weapon (say, because it returns anyhow), you just can't express that idea in the first place in a way the affected creature would understand in it's limited state. That happens to nicely tie in with the limitation on daily/encounter powers - which can't be performed either, after all. At least you could rule that dropping or sheathing a weapon is the best you can do - not the abnormal action of throwing.
Alternatively, you could look at monsters and decide that the lack or presence of a weapon shouldn't be as critical for PC's as it is; in short, the mechanical defect isn't that throwing down a weapon is
possible, it's that this makes a +12 difference to attack rolls (and is similarly devastating to damage) -
that doesn't make any sense given the way monsters work. So, grant inherent bonuses to unarmed attacks (including math-fix feats like expertise). Sure, you'll lose damage, but it's no longer crippling - actually, it's probably almost always unwise since charging and provoking OA's works quite well, and if there's a cliff, charging over the cliff is probably worse than throwing away a weapon - especially since a dropped weapon might be picked up again.
Another option would be to simply accept the issue and make an adhoc fix to work-around it the first time it comes up, but then to state that this is a common enough risk that all adventurers habitually carry an extra weapon or implement or two. If these are 5 levels lower, then the cost is fairly minor (and in any case, you probably have old weapons lying around), and doing this completely destroys the strategy - suddenly dominate turns into a mere -1 attack and damage for the rest of the encounter or until you can pick up the weapon again as a minor action - certainly not as attractive as the alternatives. As a DM, I'd be perfectly fine with retconning that logic into a campaign: "
poof, didn't you know all adventurers have backup weapons?"
You can even combine the three - you can't throw, merely drop a weapon (perhaps into an adjacent square), you can fix the mechanical flaw that is the discrepancy between unarmed PC and unarmed monster attacks, and you can institute a rule that it's expected for all armed creatures to have a reasonable fallback weapon.
What you should not do, however, is just say "that orc shaman over there wants to kill you - but he's nice enough not to really try". That undermines the very essence of the game - at least, if flavor matters (which admittedly it might not in humorous games or in groups focused on the tactical game).
requiring the great axe, and was made to throw it, well, he's weaker until he gets it back.
