M5E vs CM in battle
As I said - if you need a special CM in battle because his random magic allows him to cast a spell you want - go and use him. But better deck him out and maybe even empower him in Astral: It's not only that cheap S-1 mages could duel him to death easily (AI won't do that, though), in my experience there are few arrow magnets like 250gold mages. And CMs aren't really as durable as Jotuns ... . When I played S&A, the mean time of survival of my CMs was 3,5 battles unless I gave them shield, armor or items.
And
more magic pathes isn't necessarily what you need in battle. Only gives the spell AI more chances to screw up. And both will be able to get Fire, Air, Earth - 2. You may get lucky with a Water-3 CM - I would suggest using that commander to go underwater, casting Geyser.
Masters of the Way
Are lousy combat mages. Yeah, sure they can cast quickeness. But the Fire/Air/Nature-1 from a random will only let them cast low-level spells with high fatigue cost. Most of the time they will be sitting around buffing themselves... . Better forge some Sceptres of Authority and let some indie commanders or Black Servant use those: Casting spells from an item is only 5 fat/spell.
bless
With all mages and the national summons blessable, I would
at least go for an earth-4 bless to give everyone 2 reinvigoration. Means the mages might get off one more spell, and the Demons never tire from combat as they only have enc-1 - they might even recover from fatigue-inducing spells. Air shield from low-level Air blessing isn't worth it, but the shock resistance from Air-9 might something to be considered (if it where 100%, even more so
)
Nature-9 might be tempting, but stay away from it: berserking mages aren't really a good thing
Death-4 isn't really worth it: most times you'll have too few Demons in the front line for it to have any effect.
.. will add more later, have to leave now ...