The trope of a pre-gunpowder warrior who can swing his sword or axe with such aplomb that he survives multiple battles despite being in the thick of the action is pervasive in fantasy, but how frequent was such an occurrence? We have the weapons, the armour, the ranks and the rewards given out by victorious leaders, so we must surely understand how frequently a warrior of renown actually fought?
Although there are multiple lenses through which this question can be interpreted, generally speaking there's no real history behind the trope of soldiers breaking off into single one-on-one duels (or in some cases, many-on-one duels). Between the bronze age and the gunpowder age large pre-modern militaries valued compactness, order, and discipline (at least in Europe).
I'm most familiar with militias in the Italian context, but the trend is a fairly consistent one: pre-modern battles were fought between tight formations with polearms. There's some discussion to be had regarding the specifics; some argue that battles resembled masses of people grinding each other down, while others argue that two battle-lines would reengage and disengage for multiple short periods over the course of an engagement (I'd say it was probably a little bit of both depending on the situation). A more open melee would only ensue if one of the two infantry formations broke and fled, which is when most casualties would occur.
I wrote a few answers on medieval battlefields you might be interested, both here and this answer on swordsmanship.
Just to reframe your question: about how many unskilled soldiers was a skilled, career soldier worth in medieval Europe (any sub-period of "medieval" is fine)? Is there a way to factor this in without differentiating between equipment quality?