It should only play the backstabbing animation when you are actually behind someone for it to happen. Also, it should play a different sound / different damage type / different CI.
The "CI" image seems to be the item icon image as well, not coloured red like all the rest of them and is absolutely massive. This does not help when you kindly added a force downloader to it.
This also has the side effect of causing every weapon to backstab if you happen to be perfectly aligned with the person you are attacking, for instance via setPlayerTransform or the place you spawn in. Check if the projectile's backstab radius is greater than zero.
One last thing, AIPlayer inherits the functions from Player. You do not need AIPlayer::getRotation() since it'd call the identical Player::getRotation anyway.
EDIT: I didn't read the code well enough.
