The ability to detect lies and discern truth through subtle cues in speech, body language, and psychological insight..
Out of combat, you can tell if anyone is lying to you. You cannot discern what they are lying about though, unless the GM allows you to roll for a higher DR. Might require an opposite roll if they are skilled in lying a hiding thougths.
In combat, you can read opponents you are engaged with, and can see if they try to feint attacks or similar with both weapons and spells. This will be an opposite roll against the feint.