This glitch occurs when, at any time during a single player match of any type in Halo: Reach, a new player locally logs in and initiates split screen. If this new player has a Sangheili archetype selected and the game mode permits its use, then this glitch may activate.
Effects[]
This glitch causes an interesting cosmetic effect. To anyone else viewing, your character appears to be a completely default Spartan, but in first person the character's arms and legs appear to be that of a Sangheili Minor without the armor on the wrists. There do not seem to be any adverse effects on gameplay.
Causes[]
The only known cause is to sign in to a game already in session.
Fixes/Prevention[]
The only way to fix this glitch is to die or respawn, and there is no way to prevent this from happening.