Three ways to get the exotic. One with pvp only One with pve only One with both. When one finish it one of these ways it locks to that area . You're good with just using the weapon in pve, then just do the pve requirements and so on And of course doing it so it unlocks in both modes should be harder cuz it unlocks in both. At least what i think. And maybe to prevent that one just do the pve first and pvp next, maybe one more damage bonus or something?