update, developer Bungie makes it absolutely clear that players will not be able to swap weapons and gear within the open-universe first-person shooter.
A fan asked Bungie if player-to-player trades will be available at Destiny's launch and was met with a succinct denial. "Nope. We want you to earn 'em," Bungie stated. "You should be able to tell a badass story for every sweet jewel in your arsenal." Though trades between players will be lacking from the game, Bungie does note that players can trade items between their own characters. "Once you earn them, the various Guardians under your account will be able to trade them, but weapons belong to the players who acquire them through action and bravery."
If you're now grumbling in frustration, have a look at Sony's official unboxing of the white Destiny PlayStation 4 bundle below the break. It's not a replacement for a proper, player-run economy, but maybe watching the birth of a new gadget will take your mind off of things.