So, let's look at the Wars. They have one offensive skill -- Death From Above, and one (the best) defensive -- Create Distance. You need then switch between Tank/Parry or Parry/"Bash" in order to allow a good work of these skills.
But that's what makes Wars so fun to play with - you need to set up a flexible strategy (which admittedly is harder now with the wider variety of available builds) but if you do it properly, they can handle pretty much anything. With the Slayer you get a Rage with better armour and worse offense and one way or another you'll come down to the 2-3 lines strategy typical for the Waaaaagh!!! builds. Not my cup of tea but somebody may like it enough to have the patience to find a way to control all these activated skills and ultimately produce a competitive gladiator.