1000 yard stare

A battlefield syndrome in which a soldier may become lost in thought due to stress from the fight. The 1000 Yard Stare is named such because the soldier may seem to be focusing on an object very far away, and may even become unresponsive to external stimuli. The phrase was coined during the Vietnam war.

You'll find that the phrase was in fact koined during the Second World War and popularized when a painting of a Marine exhibiting the stare was accompanied by a notation to the effect that Marines referred to the look as a "two thousand yard stare". However, the stare itself has been known as long and man has engaged in persistent, long term combat that resulted in Battle Stress Disorder.

Staring into nothingness whilst one's mind is occupied or is completely empty.

a high impact sniper rifle in destiny widely used and considered the best pvp sniper

The ability to tell (from 1000 yards or better) that a person of the opposite sex A) Has a case of fugly face B) Has perpetual bad hair days strung into a "life" C) Is so ugly that no amount of Alcohol in the world can make them look better D) Could benefit from a paper bag on their head

This stare can be useful for finding attractive people as well. You will find this useful when you need a wingman (or wingwoman) for a night, or twenty.

a high impact low rate of fire sniper rifle from the vanguard, also widely considers to be the best pvp sniper currently

The 1000 Yard Stare, or the 2000 Yard Stare, was a symptom of battlefield stress and exhaustion. It became named so during World War II, because the victim would become unresponsive and stare "a thousand yards off".