It seems that other than the Warlock, there really isn't much value to purchase/add the Pit Fighter or Knight. They have the similar capabilities and stats as the normal warriors only that they start with a higher level and let's be honest, their equipment isn't that great either. My suggestion would be to add some uniqueness to Hired Swords in the form of unique skills that only they have access to. For example, the Warlock is unique in that he has magic skills. So perhaps create a unique skill available only to Pit Fighters and another one only to Knights, or if it is easier, perhaps let Pit Fighters have a starting max WS of 45 and Knights perhaps a starting max Strength of 45? I know that Warlocks already have a max starting Initiative of 45, so again, another unique aspect of the Warlock. This would be a win/win as you would be able to sell more of these and players have incentive to purchase them.