These are just the concepts of headshot and backstab animations I came up with for each class
Flanker: The bullet hits flanker in the head while running which makes him do a backflip for some reason and then fall onto his back
Trooper: The bullet hits his helmet so hard that it lodges the helmet into troopers skull with trooper trying to remove it while falling onto his knees and then finally falling onto the ground
Arsonist: A chunk of Arsonist head is shot off revealing cogwheels and wires with arsonist freezing in the pose he was in while falling in a random direction
Annihilator: the bullet breaks his googles and Annihilator tries to remove the glass but then falls face first onto the ground
Brute (primary out): His head is knocked back and he falls onto his minigun
Brute (with secondary or melee): Brute stops the bleeding on his forehead while he takes a step back and trips backwards onto the ground
Mechanic: His head is knocked back a little with his arms swaying and then slowly falls forward
Doctor: he drops his arms onto his side and spins once and then falls to his right
Marksman: his weapon slips out of his hands while he falls backwards with his arms falling onto his side
Agent: agent for some reason flies backwards by a little lying on the ground
Flanker (These ones are backstab animations): Flanker trips and flies forward
Trooper: Trooper leans backwards due to the pain but then the weight of his arsenal causes him to fall backwards
Arsonist: there is a large cut on arsonist back with wires coming out of his back with him falling onto the ground
Annihilator: Agent stabs the back of Annihilators neck since his vest prevents backstabs, so Annihilator stops the bleeding but then falls onto his knees and then falls onto the ground
Brute: Brute stops the bleeding on his back while leaning forward and then falls face first onto the ground after a second
Mechanic: Mechanic leans forward while putting pressure on his back but then falls onto his back after a second
Doctor: Doctors medi-gun machine is sliced causing the machine to break and electrocutes the Doctor making him fall forward
Marksman: Marksman drops his gun and holds onto the wound while leaning backwards then leaning forwards before falling onto the ground
Agent: The Agent shoves her knife in the other Agents back making the other Agent fall onto her knees and then falling on the ground