This happens when you leave Fort Joy before you talk to Borris OR if you do the "Hammered" achievement, because from the note alone Ifan doesn't get the idea that he could ask this Zaleskar guy for the weapon, even though the questlog says otherwise after you pick up the note from his dead body ("Hammered" achievement inevitably means that Borris dies as well, because he is around).
Clearly a bug.
