>>546378161
High damage resistance so they can tank bullets and destruction. Though the amount they get varies and higher powerlevel girls are even tougher and can heal faster (during Eden Treaty both Hasumi and Tsurugi are caught in the explosion. Tsurugi explicitly got less damage and healed faster than the Justice Task Force).
The average power strength is also higher than the human baseline with Sensei being only able to keep up with the more sedentary Millenium girls. Even then people like Kotori can run around with a minigun (though the stronger Nonomi visible wields her minigun without any recoil).
Again, stronger girls will have superhuman strength with Neru and Kanna running up on buildings, Mika breaking walls barehanded, Tsurugi at one point just going melee and breaking Akari's arm no gun needed etc.
Their guns are all real. In fact they probably use guns because it's easier to hurt each other with them since only the fewer stronger ones have brute force to hurt others without one.