On Io there is a Warmind Vault named JYS-2. What could this mean?
Could it be related to the Warmind Charlemagne? JYS do not seem to related to Charlemagne in anyway, until you look deeper.
Charlemagne had a personal sword named Joyeuse. This could be the connection to Charlemagne and JYS. It may seem like a stretch, but it actually goes deeper than that.
Bungie has three main games: Marathon, Halo and Destiny. The main AIs in each game are as follows:
1. Durendal - Marathon
2. Cortana - Halo
3. Joyeuse?? - Destiny
A sword named "Cortana", "Curtana", etc., was also attributed to Ogier the Dane, one of Emperor Charlemagne's paladins in the Matter of France. According to legend, it bore the inscription "My name is Cortana, of the same steel and temper as Joyeuse and Durendal"
Interesting fact: Some tales of Joyeuse claim that it has a connection to the Lance of Longinus, which pierced Jesus when he was upon the cross.
The Lance of Longinus is commonly refered to as the Spear of Destiny.