I hate to say "well it depends" but... well, it depends.

Weaponry for personal combat and for battle is cultural. Your choice of weapon is going to be driven largely by the overarching social organization of your society, and by its access to certain resources, logistical chains, and regional characteristics.

Further, your access to anything other than what was handed to you is going to depend on your class. Are you a peasant rebel? A conscript? A volunteer yeoman? A landless man-at-arms? A professional soldier? A mercenary? All of these will change your choices - if you had any at all - and in general, your options are going to be driven by what your region produces or imports in bulk, what you've spent time working on, how familiar you are with weapons and what your social standing is within the military sub-community.

Certain communities in the medieval and early modern era basically proscribed certain weapons and skills as necessary for a serving citizen or member of a local militia. Ordinances maintained that, for instance, every citizen (of a specific class with respect to land ownership or whatever) might need to own a crossbow and a certain amount of ammunition, a sidearm, and something like a breastplate and helm. Another town might require citizens to own pikes or halberds, a sidearm, and armor. Still others might require a lance, armor, and horse.

It depends very largely on the cultural context in its specific place and time. Variance in sidearm would likely be expected, but it would be difficult to get hold of something non-local unless it was regularly imported, which limits a lot of options. Battlefield loot could provide other things, but -in general- you'll find a lot of military units tend to have certain fashions and trends that everyone goes in on.

This is a somewhat general answer and I go into a bit more detail about this dynamic on an earlier post here about the cultural dynamics of armament.

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More info on the early modern side of things as relate to citizen militias is in Ann Tlusty, The Martial Ethic In Early Modern Germany

Another good one is David Parrot, The Business of War, about the social and economic dynamics of mercenary groups in early modern Europe.

Generally speaking, someone who could be called to serve in a medieval army provided their own equipment, but were required by law to come with a certain minimum set of gear. This usually varied either by social class or income and often included a few different options which would be acceptable. For example, a fifteenth century Scottish law required yeomen with less than £10 worth of land to have 'sufficient bowes and sheaves, sword, buckler, knife, speare, or any gude axe instead of bow' which isn't terribly clear, but seems to be saying that a bow, an axe, a spear or possibly a sword and/or shield and/or knife would all be acceptable. Or it might just be a wordy way of saying 'some weapons'. Other laws were a bit more restrictive. In some cases there were standards specified for the equipment, but mostly that seems to have been left up to the soldiers, so even if you were required to bring some kind of sword, you had a lot of options with regard to what you favoured.

I don't believe there were any laws saying you couldn't turn up with more than was required and it seems that knights at least would often carry maces, axes or flails when they were typically required only to have a lance and sword. Obviously having several large weapons like spears and bows would be impractical for someone who wasn't travelling with servants and horses, so a typical free peasant probably only had the option of either a bow or some kind of spear or polearm as their primary weapon. However, they would likely have had a wider choice of 'sidearm'.