[Logic_]

PHP код:

                new Float:armour, Float:hp;
                GetPlayerArmour(playerid, armour);
                if(Float:armour > 0.0)
                {
                    if(Float:armour > FIST_DAMAGE)
                    {
                        GetPlayerArmour(playerid, armour);
                        SetPlayerArmour(playerid, armour - FIST_DAMAGE);
                    }
                    else
                    {
                        new Float:newer;
                        newer = FIST_DAMAGE - armour;
                        SetPlayerArmour(playerid, 0);
                        GetPlayerHealth(playerid, hp);
                        SetPlayerHealth(playerid, hp - newer);
                    }
                }
                else
                {
                    GetPlayerHealth(playerid, hp);
                    SetPlayerHealth(playerid, hp - FIST_DAMAGE);
                }
            } 


Your code isn't perfect, see my code and you will understand, and yes, its your anti-cheat fucking with it.