If you look at the vanguard class emblem, it's almost like it's missing something.
It has the titan, warlock, and hunter class emblems on them and then a 4th, almost just...space wasted slot.
Is Bungie just being lazy? Probably.
Perhaps it's just insurance in case the team decides to throw in a 4th class.
I like to think maybe they got something random in the back of their minds.
Food for thought...
Back in the day there was always speculation that the space would be filled by a fourth class but that’s more or less been abandoned as a theory now.
The likelihood is that the crest shape didn’t accommodate 3 classes with equal space for each so they just filled the last quarter in.