Firstly, I’d say that battle brothers is more well represented by the high middle ages rather than the late, which did not have firearms. Battle-brothers is a low fantasy – aka gritty medieval world with some fantasy elements, so no, guns would just be a strange addition. You can easily solve the lack of ranged weapon variation by adding different types of crossbows or something.
As for the claws – not sure exactly what you mean by them – but they sound like some fantasy ninja weapon which again doesn’t fit the setting
