I've done some asking around and personal research in-game as well as on the forums.
During the TPN trial, you fight Maelstrom three times. The first time, he's Dual Pistols. The second time, he's only got one pistol and uses a Marked For Death move. The third time, he's pistols-less and uses teleportation and Martial Arts (including a variant of Vorpal Judgement) instead.
For those first two fights, he "loses" a pistol on defeat. According to my source, one of the UStreams mentioned a 4% chance of it dropping into a random Leaguemate's inventory (provided they have room for it) both times. That is, a 4% chance for ONE recipe to drop to a random Leaguemate. We should look up that UStream.
There is only one recipe, but you need two of them if you want to be dual-wielding Maelstrom's weapons. I'm told any Dual Pistols or Thugs character is allowed to craft them, but cannot verify that at this time. Additionally, I've heard that the recipe becomes available for Incarnate Merit purchase of some sort, but it doesn't show up in either vendor on my Thugs, although that character hasn't run the TPN trial.
The recipe may be traded and sold on the market.
