Although all Demons of any power are accounted for in the rosters of the seven (now six) Demon Masters, the "Elite" of each Master are often shaped or specialized to better represent the Demon they serve.

My chosen are of course fully armored, and are given a portion of my Ever Burning Energy to use. They are not to be sacrificed lightly.

Sangui's Elite are granted weapons forged from her liquid body. Sometimes the liquid can even pass into them, something I am surprised does not result in chimeric fusion.

Buzhum has mostly intellectual elite, each of them given one of the "split selves" to help with their work and study. And of course to monitor them closely. The weakest of the Elites in terms of raw power by quite a lot.

Jern is too vain to share any of his own self with his elites. He does however only select the best he can, and they get access to incredible favors. He has very specially sculpted "Hand Demons" that are more art than function, but are still dangerous.

Vapula's Elites are by far the most dangerous. They are given training, energy, and top class armor and weapons. Vapula personally teaches and instructs each of their Elites. Those who cannot keep up are discarded or even killed.

Bael seems to put little thought into her Elites. They are mostly just her most competent demons. She does talk with them frequently, and they are all supposed to be highly loyal and motivated. Much less regimented than the others. 

-Part of a detailed report by the Demon Master Dzu