dvang said:
Pretty much what Haggard says. Since we don't currently have a "Mercenary Sergeant" career for a Mercenary to advance into ... he can approximate by using a Thug as an approximate template for how a "Mercenary Sergeant" could typically feel. He could advance into the Thug career card, yet still remain a Mercenary "sergeant".
There is a big difference between using a Thug to represent a position in the chain of mercenaries, and using, say, a Scribe to represent a Dragon Slayer, or an Ironbreaker for a Cartwasher (if there was a cartwasher career). I'm suggesting that it isn't difficult to find a similar and compatible basic career to represent a more 'advanced' type career position with the current career cards. Will it be nice when more advanced career cards come out? Sure! Is it something urgently needed? No, because for the most part, the basic careers make fine alternatives until then.
I think this way gives the player a lot more options, as well. Military Sergeant doesn't really say anything about the character. Maybe he brutalizes his men to get things done (Thug), or maybe he spends his time in study pouring over texts on military tactics and strategies (Scholar). Maybe he deals in logistics, making sure that each unit is properly supplied (Bailiff). Perhaps he uses his position to illegally sell weapons and armor to the highest bidder (Smuggler).
Each of those adds much more flavor to both the character and the campaign than just plain Military Sergeant.