AoB on medium difficulty isn't something you need to cheat in order to win--it's very hard until you get the chainsaw but after that it's not at all. So you need to be very careful before you get the chainsaw, avoid fights and use "cowardly" tactics, until you reach the Chained Court.
About "cowardly" tactics: by this I mean that you need to find ways of getting your enemies near you without having to run at them and take damage as you charge them. For instance, carry extra pistols; if you drop one in a doorway and then duck behind the doorway, out of sight of an enemy, it will come to the door to pick up the pistol, at which point you can attack them and you will already be right next to them, instead of being far away and having to rush at them while they shoot you.
High-priority traits in an AoB game are Brute, Berserker, and Hellrunner (you should probably max these out), and it's very helpful to take a level of Eagle Eye, too, as your accuracy in melee is surprisingly poor without it.