By this, I mean like there are the Catachan blades, but no Catachan warriors; it would be kinda awesome to be able to make yourself into one. Perhaps even have that as a kind of primary class choice; you’re from Catachan, and thus very good with blades and and to hand.
This would allow for a lot of variations on just ‘prisoner’ or the existing classes, and make for a more diverse classification for the players and teams that get formed. And I know 40K has a WIDE range of ‘humans’ to choose from.