Drop the longing to make humans juggernauts in the RP and simply go with the idea that every faction is more or less capable of great destruction. Unless you have someone in this RP trying to waltz in here with cannons that fire singularities and starship armor comprised of pure neutron star matter, everyone is more or less going to be on the same playing field.

Once a civilization achieves FTL technology and has the ability to traverse planetary systems with relative simplicity, you're looking at a species that can throw around firepower [i]far[/i] in excess of the teraton range.

War with care is all I say.