Jon examines the slaves, some of whom flinch away from his presence despite his deliberate moves, but sees nothing worse than some chaffing around their manacles. Certainly none as badly injured as Tyr. It looks like whoever bought these slaves was looking for healthy adults, there are no children or elderly among them.

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The blunderbuss is of the battered variety, a gunslinger's starting weapon. It's considered broken for anyone else trying to use it, so you'll have to put in the 1 day of work and 300 GP to remove the battered condition and get it back into masterwork shape to use it safely (the rules suggest that a gunslinger can't upgrade someone else's battered gun, but I'm ruling that you can).