How about this to replace sneak attack damage:
Study Specimen: At 1st level an Investigator may observe one enemy as a standard action making the appropriate knowledge check
needed to identify the creature. If this check is equal to 10 + the CR of the creature the Investigator receives an insight bonus to hit and damage equal to her level but not greater than her intelligence modifier. she receives an insight bonus to her AC equal to half this bonus (minimum 1).
If there are more than one creature with identical stat blocks (multiple rust monsters or hired thugs) in one combat this bonus applies to all those creature.
If the knowledge skill fails, all creatures of that type in that combat are immune to Study Specimen for 24 hours. These bonuses last until the creatures are dead, 24 hours have past or she chooses a new target to study. The Investigator can only retain her bonuses against one set of creatures at a time.
Baneful Study: At 6th level whenever an Investigator succeeds a Study Specimen knowledge roll by more than 5 (CR + 15) all physical attacks made against the target are treated under the Bane effect, +2 to hit and damage, +2d6 untyped damage).
Nemeses: At level 12, while using Study Specimen, if the Investigator's knowledge check exceeds by 10 or more (CR +20) she gains 4d6 damage with her Baneful study ability instead of 2d6. Likewise She can target 2 creatures (or groups of creatures) in one combat that have different stat blocks so long as they both fall under knowledge skill.
Capstone: As written but using Study Specimen is now a free action.
