3 of those mentioned are general slavic.
Namely:
Voi - (literally meaning warrior) was probably the name used for any armed man, even before Slavic split.
Word itself comes from proto-indoeuropean wey - to chase, pursue or drive away.
Voivode - (literally one leading warriors ) similarly used earlier as general slavic word for leader of group of armed men. Possibly the same word was used for warlords chosen in case of war for early slavs.
Druzhinnik - a member of druzhina, (where drug, druh literrally means companion, so druhzina - companionship) - mostly known from Kievian Rus and Poland retinues of knyaz/książe (read ksionge), but probably meaning any kind of long existing military group (as opposed to temporary ones made only for battle).
Slavs being rather defensive (almost every settlement was surrounded by heavy defensive infrastructure) mostly used a system of tribal democracy. Decision making was made by veche - a kind of public assembly, where all adults would decide what to do. Possibly the decision was pre-disscussed by elders to present ready solutions to general population to decide from.
They knew however, that while it's great system in peace - in case of big military threats, a war - it became insufficient.
So they could have decided on choosing war leader.
In turn settlement war leaders could meet and decide on a leader among themselves, creating bigger, functioning army.
Druhzina could be some kind of military element even then, but there is also a possibility, that it only started to appear around the time varangians came to slavic terrains - ready to be hired.
While some historians believe varangians themselves created Kievian Rus, much more probable is the theory, that they were hired (or promised something, like land), thus creating cores of first druhzinas.
And there is also something funny - significant part of mentioned and related units are already in the pack:
- Slavic Veche Izba - slavic factory
- Druzhinnik - elite heavy infantry
- Voivode - heavy cavalry leader
- Boyar - mounted archer leader
so the slavs political system was kind of parliamentary?, besides i find new russian troops quite interesting, however there is only the strelet.
I swore to protect and lead a great order that seeks enlightenment, I was chosen by the great star and I will pour out his fury against anyone who declares himself an enemy!
