Hmm. Well, Sword = Halos, Shield = Onyx, Ark = Ark, ala Halo: Ghosts of Onyx. What you said is true, but I think we can take it a bit further. Shield = Halsey/Cortana, Onyx Sword = Gravemind/Cortana, Halos Ark = Durandal/Cortana, Ark on Earth Maybe Durandal and the things in Marathon happened the Forerunners' time? Like things repeated? I dont know, just a thought. I am almost certain that was Halsey speaking of the Shields, and I know Gravemind may have some access to at least one Halo (Sword).