I have buried away somewhere the full description but I based the Int modifiers I believe were the same as the benifits/penalty of strength when using a blade Minumum Int=5 or a -2 to roll Int=9+ granted +1 to roll and the weakened modifier was a -2 for like being intox or illness affecting mental abilities. This was being you needed to be smart enough to know what was happening, and if you was very smart you knew a little bit more of your situation. And yes if a player could make a good solid argument as to why they would get the roll then they would get one. I had to make it harder for scouts to get the skill as they see such a variety in chargen that where would they not get the roll. As they can be considered a combat, pilot, medical career, they might even see some merchanting when they needed certain supplies in the career.