: Do we have an understanding of what the Guardian of the Luminous Key is at
: this point? I had the thought that it was supposed to be the Arbiter, who
: was supposed to have been one of the Sangheili on Ascendant Justice before
: a retcon in the HGN, but I then read a theory that the Guardian was the
: name of the Covenant AI, which has been suggested to be a massively
: degraded Cortana copy from the attack on Unyielding Hierophant. If this is
: true, the Luminous Key could be either the Forerunner crystal or the Index
: that Cortana absorbed from Installation 04 that the Covenant could have
: intended to use to activate Halo.

: Do we have a consensus on this, or is this just old conjecture never
: resolved?

Never resolved, but I remember people agreeing (at this seems to be the theory that the Halopedia editors have rallied around, judging by the wiki entry for same) that it might just be a ceremonial title for the bearer of the Activation Index—not necessarily the Arbiter or any field commander. There's no indication that the Covenant knew Cortana had the activation index so they might still have been searching for it.