A little input about archers from a historical point of view from an amateur historian;
Archers generally could be divided into two categories; levies with bows and professional archers. The former are what you probably have in mind; people who can shoot bows that you draft for war that will run at the first contact with the enemy. The latter however are professional soldiers. Professional light infantry that excell with their bows or missile weapons, but are not a one trick pony for sure. They often had very good quality armour and would not shy away from a melee fight, provided that it was not standing up to a cavalry charge on a flat open field. The most commonly cited example would be the English longbows descending on the French dismounted chivalry stuck in the knee-deep mud at Agincourt like packs of wolves after firing their arrows point-blank into their ranks.
I know for example that in the English armies of around 1370-1410 there were generally speaking only archers and men-at-arms on the payroll, aside from knights and nobles. The archers were paid the least, but still a respectable sum (would have to look it up again to give numbers, sources and more context in general). The men-at-arms were paid a bit more than that, and were expected to bring varying forms of 'heavy' equipment. It should be noted in this case that very often archers would try to join the payroll as men-at-arms for the additional income by gathering the necessary armour and equipment, which they would undoubtedly also use.
In history there's often been both and mixed forms of these. Not all professional archers were necessarily well-equipped or heavily armoured (a quick glance at Arabic and Eastern cultures in general), nor all unprofessional ones were shy from melee combat (town militias in some cases).
Translated to M&F; Would these be easy to distinguish? Well, how easy would it be to distinguish professional soldiery compared to relatively unwilling men on campaign? Remember that actually fighting is such a little part in a soldier's life, and that wearing armour on the march is something only done when fearing ambush or when deep in enemy territory, making that argument moot in most cases. Recognizing a professional fighting force from a less organised one however, is not too difficult.
Disclaimer; take my words with a grain of salt. An amateur historian is me.