Alchemy +3 (Su) +2 to Craft (Alchemy) to create alchemical items, can ID potions by touch.
Armor Expert -1 Armor Check Penalty.
Canny Observer +4 vs. traps and eavesdropping
Ceaseless Observation (Ex) Use INT instead of CHA for Gather Unformation (+5)
Combat Expertise +/-1 Bonus to AC in exchange for an equal penalty to attack.
Darkvision (60 feet) You can see in the dark (black and white only).
Elf Blood Half-elves count as both elves and humans for any effect related to race.
Elven Immunities - Half Elf +2 Racial bonus on saving throws against enchantment spells and effects.
Elven Immunities - Sleep You are immune to magic sleep effects.
Half Drow Inspiration (+1d6, 4/day) (Ex) Use 1 point, +1d6 to trained skill or ability check. Use 2 points, to add to attack or save. The investigator can use inspiration on any Knowledge, Linguistics, or Spellcraft checks without expending a use of inspiration, provided he's trained in the skill.
Keen Recollection Can attempt all Knowledge checks untrained.
Light Blindness (Ex) Bright light blinds for 1 rd, then dazzled as long as remain in it.
Power Attack -1/+2 You can subtract from your attack roll to add to your damage.
Trap Sense (Ex) +1 bonus on reflex saves and AC against traps
Trapfinding +1 Gain a bonus to find or disable traps, including magical ones.