I couldn't miss the chance to practice my drawing!
Seigan is Samurai job ability gained at level 35. It may be used once per minute and will remain in effect for 5 minutes. Seigan may not be active at the same time that Hasso, another Samurai ability, is active. If Seigan is used while Hasso is active, Seigan will overwrite Hasso, and vice versa. While in effect and only while a Samurai is wielding two handed weapons, it will drop the reuse timer of Third Eye from 1 minute to 30 seconds. Also, there is a change that the effect granted by Third Eye will last more than 1 hit and that rather than an enemy just missing the Samurai, the Samurai may Counter-attack. The chance of countering is very small, and while the exact percentage is not known, it is in the area of 3%.
Seigan (正眼) (Lit: Angle of the eyes) is a basic defensive stance. Specifically it is the preparation for an enemy's attack by aiming the sword at their eyes. This stance is also done with the left foot back and the right foot forward, giving the defender a much better ability to step backwards while limiting their ability to attack. It is common to assume this stance immediately after drawing.