Quote Originally Posted by DarthEnderX View Post
Arcnologia is also, like, the MOST powerful dragon(and not even really a dragon), so I don't think he's a good judge of the power of your average dragon.
Not per se, but we do know all the toughest Fairy Tail members together were more or less helpless against Acnologia. So, even if an average dragon had only a tenth of Acnologia's power, Sting & Rogue back then wouldn't have stood any chance. That's why I'm confident in saying that there's no way they could have killed their dragon masters in a fair fight.