The description is rather short. It reads,
The common soldiery of Firstborn armies is composed of levies and militia, with a core of professional troops such as city watchmen. They are equipped with a broad range of weapons such as spears, short swords, hammers and axes. Many wear little in the way of armor though the professional guards often wear chainmail. They are good all round troops who fight with passion and conviction.
The picture shows a knight in full Firstborn armour brandishing a straightsword, with an irregular horde of soldiers behind him who appear to be armed with axes and swords.
We included house-rule militia in one scenario, where each warband of levied men (only minimally armoured in tunic and chestplate, and armed with hand axes) was led by an Iron Guardsman armed with a straightsword and shield. I imagined them to be citizens, craftsmen and peasants taking up arms in case their city was threatened.
I felt that this would be a rather effective use of those untrained troops, placing groups of them under the command of an experienced veteran, who would also be responsible for their training during peacetime. Since the Iron Guard patrols the cities of the Firstborn, home defense would naturally fall under their jurisdiction as well.(edit: picture)