The adventurers in my classic fantasy world have access to all sorts of potions. Some, like health potions and their more expensive cousins like regeneration potions, can bring people back from being nearly dead. The utility is obvious, and no sane adventurer or fighter of any sort would ever leave home without one. This leaves a slight problem though: potions are very magical and reactive substances and need to be kept in non-reactive glassware if you want it to keep for more than a week or so. Yes, specialized carriers and metal-jacketed potion vials exist, but they remain fragile and something that needs to be protected.
This brings me to the question:
Where are the best places on the human body to store these potions? Presumably, they are kept in some sort of holster or bandoleer, but where should this be? Under the arm? On the belt? Where, for example, did knights keep fragile things when heading into battle?
They need to be easy to access in case of injury. Ideally, retrieving one is a one-handed operation.
They need to be somewhere protected from the rigors of combat and any other extreme movement their owner might get about
The position of the holster shouldn't prevent things like climbing ladders or riding horses