When does an axe stop being an axe and instead becomes a polearm?

Is it based purely on the length of the haft or a combination of the length of the haft and type / function of the axe head?

Was there any distinctions made in medieval / renaissance times regarding this or is this similar to the usage of other terms and names which were very flexible in their meanings and descriptions (eg buckler described as both a hand held shield or a shield strapped to the arm - a targe)?

Has there been any clear distinctions made my medieval scholars over the years?

Are the following all classed as axes or polearms?

Bearded Axe, Danish (Breidöx) axe, Kern axe, Sparth, Ōno

Are there any other axes that I've missed (large 2 handed axes with long hafts)?

Thanks

Danny

This is a deeply disfunctional field of arms studies.

Some axes are polearms. Some polearms are axes. My own rule is that if a hafted weapon requires two hands for effective use, it's a polearm. That means the shortest weapons I consider polearms are axes of waist height or a bit below, depending on the weight of the head. The two-hands rule (as opposed to a static length rule) eliminates weapons such as lances and darts/javelins, which are as long as spears and resemble spears but are used with one hand (and, in the case of darts, are actually missile weapons). It also eliminates horsemen's hammers and maces, even though those might technically qualify as "hafted weapons".

I doubt that our ancestors were particularly concerned with classification and typology beyond the broadest categories, and then only for specific tactical or documentary purposes (the pikes should be here, the halberds should be there, the Gallowglass carry axes six feet long, etc). If they had cared much about details they would have imposed more order, and thus we'd have much more order and understanding in our modern study of what we call polearms (or hafted weapons. or staff weapons. We can't even agree on what to call this category, much less what to include in it). When they wrote of halberds and pikes and axes, it was simply understood what they meant. The fact that some period martial training texts advocate for specific weapon styles and lengths suggests that there was difference of opinion on optimum style and length, and in fact we see variation in the length of original hafts. Even a cursory glance at historic illustrations of combat reveals an enormous variety of polearm types and lengths even on one side of a single battle. Somebody should go through the illustrations of Froissart's Chronicles and count the different polearms on display there because the variety truly is amazing. And those illustrations are relatively late, from the last quarter of the 15th century. We see more standardization in later polearms, but that seems to be due to the fact that individual manufacturers were churning out hundreds of these arms for arsenals rather than due to some desire for military uniformity. The point is, if you have 500 men with halberds of slightly differing length and form, you're not going to record the details of the weapons. They're simply "halberds." They're deployed and used in the same general way to the same general effect.

Detailed classification seems to be a later development, especially driven by 19th century collectors. Because those efforts were often uninformed and uncoordinated, we're left with the twin problems of sorting-out that flawed original sorting-out as well as trying to understand the manufacture, use and strategic deployment of the arms in their working lives.