The Exotic Catalyst for Ace of Spades has a chance of dropping from either kills or completions in Vanguard playlist activities, including Strikes and Nightfalls. The catalyst, once completed after 500 weapon kills, will grant an additional perk: Exotic Trait: Funeral Pyre - Firefly deals more...
Ace being captain of the Spade Pirates is a pun on the "ace of spades", which is also named the "Death Card", a possible hint at his eventual death. In the 2nd, 3rd, 4th, 5th, 6th, and 7th fan polls of most popular characters, Ace was ranked 8th, 10th, 5th, 6th, 5th again...