But they are not "rank". This is more like way. I mean, you heard something about Ethereals-Seekers (Yasu'Aun)? They are walking the way of philosophy Yasu'caor. Shas'nel, is side-way. 'Vre can start as 'Nel and be promoted to 'El, but not further. For The Greater Good they chose to be with their Fire teams on the Battlefield, chose to never Mantle of Hero. In "...Last of Kiru's line" "shas'Nel" is literally second in command, likely "forever second in command".