Quote Originally Posted by Nagrom View Post
Our killing primals isn't unique and only something we can do. The primals have been defeated before without us and our blessing. What makes us unique is that we are immune to being tempered, not that we can kill primals. The company of heroes who we had to do all those quests for back when we were still an unknown had put Titan down. It's even stated in the Ifrit cutscenes that the Flames and Blades could put down Ifrit, just that more lives would be lost as they have to kill anyone that gets tempered.
To add to that, Tristan from the Summoner quests is heavily implied to have beaten Ifrit before (because in order to tame and summon an Egi, one must defeat its Primal beforehand); it's just that he lost his brother to tempering in the process...