In that case, you'd be hoping you either had the items at hand, or could forge them before the VQ moved off somewhere. Your still going to be relying on the random numbers generated too - a single hit doing less damage than it did in the simulator could result in an entirely different outcome.
I'd assume the simulator would be accessible from the main menu rather than from within the game itself. You could then pick your forces, mages, scripts et al without worrying about research (would be annoying if you simply wanted to find out the effect of having a mage cast one spell or another, but had to first research the spell in the game). As a side bonus, it might actually give some purpose to the battlefield designer too

(by allowing you to use the custom battlefields in the battle generator).