That's a tough call... disadvantaging the Maneaters and giving the Ironguts a huge boost. If the Maneaters were given the Banner of Eternal Flame I would have chosen them to win. The Banner of the Eternal Flame does give a unit an auto-loss against the Fireborn, but it massively helps them in like 6 other matches. But yes, you are right, the more units that take the banner, the more the Fireborn are advantaged. Personally, I wouldn't give the Banner of the Eternal Flame to anyone, it feels a bit like list-tailoring specifically for the tournament.