The battle between the Martial Sages and the Inferno Serpents raged on violently for quite some time as various factors affected the flow of the battle and its dynamics.
The Martial Sages were individually stronger, on average, as combat assets. Despite possessing the power to lay waste to much of the continent with raw destructive power, they didn't have the seamless and perfect control over their power the way the Martial Sages had. Despite possessing more than an order of magnitude more power than the sages, they could not do much more than waste it by spreading it across the entire battlefield.
The Martial Sages, with their tiny bodies, only ever experienced the minutest of the total heat of the serpents. On the other hand, the serpents experienced the full concentrated and strategically optimal deployment of the Sages.
And then, of course, there was Damian.