Ooops, before I forget: I wanted to give my armies epithets too. Iirc, an army is stratos, right? What would be...

"the Western" (because they have fought at the Pillars of Herakles, pretty big thing for them)? Hesperios perhaps?

"the First (Created)"? Protogonos?

"the Royal / King's Own"? OK that must be Basilikos

"the Loyal / Reliable"?

"the Armoured"? Kataphraktos?