When applied to a weapon, attacks made with that specific weapon are able to affect critical hits on Constructs. If the wielder of the coated weapon is a rogue, attacks made with that specific weapon can be used to perform a sneak attack on a Construct. (Constructs have no “vital” areas and are normally immune to critical hits and sneak attack bonuses.) This oil does not enable the coated weapon to crit/sneak attack any other creature type that is normally immune to crits/sneak attacks.