I'd rather leave it to my players to roleplay.
They know RQ is a deadly game compared to D&D for example and have no wish to roll up new characters every session. By emphasizing they are a part of a society where most, including "monsters" like trolls accept surrender and ransom, and their actions have consequences the worst excesses of murder hobo-type play tend to be avoided.
PTSD isn't really something you can give rules for. Its effects are longterm, not immediate, and vary considerably both in type and severity from person to person.