Why is the Ace of Spades special?
In the lengthy evolution of Playing Cards, the Ace of Spades obtained its special status through a Tax Duty collected in England since 1711. From 1765-1828 the use of stamping the Ace was replaced by a "Duty Ace" printed by the Tax Office and from 1828 onward the Duty Ace was printed with the individual card makers' name. When the Duty Ace, at that time nicknamed "Old Frizzle", was abolished in 1862, card makers were free to produce their own Ace of Spades and continued to design them as their trademark. 
The "Death Card"
It is claimed that in Cartomany the Ace of Spades predicts Death or suffering. Yet there is no genuine, historical source available that gives meanings for Playing Cards. Mostly because neither Playing Cards, nor the Tarot usually linked to Divination, have originally been employed in it. Instead, the Romani (commonly known as "Gypsies") incorporated the cards, which they found on their arrival in Europe, into their Art of Fortunetelling. http://www3.sympatico.ca/terrir/divination_index.html ]
The mystic features of the Tarot were "discovered" much later, around 1780, by Antoine Court de Gebelin. In most of the modern presentations that assert meanings for regular playing cards, the Ace of Spades rarely is read as predicting death or suffering but instead stands for change or revelations. The idea, that the Death Card actually means bad things, unfortunately remains a popular misconception among both the Uninitiated as well as Adversaries of Card Reading.
It is this misconception, that has also led to the (probably most famous) use of the distinctive Bicycle Ace of Spades as a Death Card during the Vietnam War. But instead of inducing fear and terror in the Vietnamese (who had no interpretation for the Ace of Spades at all) the Bicycle "Secret Weapon" served to raise the morale of american soldiers.
Other interesting facts not included in the article:
The figure on the Bicycle Ace is Columbia, the female personification of the Americas.
It is also possible, but not proven, that the Death Card Myth has entered general knowledge by way of an urban legend originating in Robert Louis Stevenson's Book "Treasure Island". The story features "The Black Spot", a much dreaded pirates' summons in the form of a small round piece of paper, blackened on one side and with a written verdict on the other. The character Billy Bones, already ill after a previous stroke, dies of apoplexy immediately after receiving the black spot. But historians have not found any proof of the black spot really being part of the pirate codex or jurisdiction. So pirates could not have used an AoS instead… but urban legends often contain their own confirmations.
This article was written by Novemberchild.