[Sombre]

Flaming arrows was simply too dominant a spell early on. It may not be the case any more, but people were rushing to cast it to the exclusion of pretty much everything else. And it is absolutely devastating in the early game, increasing the kill rate of archers by like 300%, if not more.

Historically nation balance has been less the target of CBM than unit and spell balance - where there have been nerfs it's because the spell or unit, as an option, eclipsed everything else to such an extent that it was simpler to tone down that option than boost everthing else.

So while easier flaming arrows would help weaker nations, its biggest change would be making everyone go after it again - provided they have archers they'd want to be casting it.