On the subject of hidden exotic weapon perks (Destiny)

by Fallout, Tuesday, March 10, 2015, 14:44 (3783 days ago)

Fairly recently I came across a thread on reddit mentioning 'hidden exotic weapon perks'. I had suspected for a while that Gjallarhorn was detonating based on proximity even though the perk didn't exist on the weapon tree, and this thread inspired me to go out and start testing these hidden perks to see if they were rumors or actually true.

While I'm glad the ones I've tested thus far have come back positive, I'm still really intrigued about the nature of these 'hidden perks' in general, as the list of exotic weapons and their corresponding perks is still mostly incomplete. Do ALL exotics have hidden perks? or only a select few?