A character with this proficiency reduces the penalties for hitting a creature they cannot see in melee from -4 to -2. In conditions of low lighting, or when the creature is concealed, they reduce the penalty from -2 to -1. The proficient character also suffers no penalties to their AC due to darkness when attacked in melee. The penalty reduction does not occur for ranged attacks, but it does help against invisible creatures. A proficient character cannot pinpoint the location of an invisible creature, but does know their general location.
Additionally, the character's speed is reduced by half as much as a nonproficient character in darkness.
The character can also use special abilities that are normally lost in darkness, though the effectiveness of these abilities is reduced by half (proficiencies, for instance, have checks made at half their normal score).
CP 4, Initial Rating NA/6, Wisdom (Intuition) / Dexterity (Balance)
A character can make a proficiency check to move at normal speed in darkness. Failure indicates they are penalized as normal.