If it helps at all... (Destiny)

by Penthesilean, Sunday, November 09, 2014, 18:00 (3907 days ago) @ EffortlessFury

...I'm fairly certain that reaching level 2 in any faction rank guarantees a piece of legendary armor as a reward, and reaching level 3 likewise guarantees a legendary weapon. With rank 4 forward, it's completely random (and usually junk blue engrams), but with a chance each time for faction-unique shaders.

That was the case for all three of my characters with all factions involved, and it was the case for my boyfriend's character as well. If that's not the case, it's been one hell of a coincidence.

That might make the work required a little bit more bearable knowing that, assuming you don't mind getting whatever the RNG throws at you.