I can give you an answer for the period approximately from 1200 to 1500, so from High through to Late Middle Ages.

Aside from the Bible and from older classical sources such as Isidore of Seville, the main source of information for medieval western Europeans about eastern countries would be encyclopedias such as Bartholomew the Englishman's De proprietatibus rerum (see e.g. these entries on Armenia and Ethiopia respectively: https://quod.lib.umich.edu/e/eebo/A05237.0001.001/1:25.5?rgn=div2;view=fulltext and https://quod.lib.umich.edu/e/eebo/A05237.0001.001/1:25.53?rgn=div2;view=fulltext) and travel narratives (the most famous example being the Travels of John Mandeville https://www.gutenberg.org/files/782/782-h/782-h.htm). The information in these sources was not necessarily reliable, but it would at least give you an idea of where these regions were located geographically. Mappa mundi such as the Hereford Map (https://upload.wikimedia.org/wikipedia/commons/4/48/Hereford-Karte.jpg) could also help a medieval person to visualise the location of countries.

There was also limited diplomatic contacts between these regions and western Europe. For instance, Ethiopia sent emissaries to Spain during the 15th century, and Frederick Barbarossa marched through Armenia during the Third Crusade. So, there would have been some degree of first-hand information circulating in Europe about these places.

The real problem comes with a particular part of your question: how much of this information would have been available to a 'peasant' (or more generally anyone from lower social/economic classes). Before the age of print, manuscripts were incredibly expensive to produce and therefore buy, and therefore generally only people from richer social groups (primarily the aristocracy, and later in the middle ages also wealthier merchants) would have been able to own them. You might also have access to books if you were part of a religious community with a library or were a priest, although these collections would usually be more focused on religious texts (e.g. priests' manuals, collections of sermons, Biblical commentaries etc) rather than secular works such as Mandeville. As a peasant, the most likely way you would have access to any of the aforementioned information about Ethiopia or Armenia beyond the off-hand Biblical references would be if you knew a particularly well-read parish priest or mendicant preacher who could tell you about it, or if you had been on crusade with someone like Barbarossa and had personal contact with people living in these regions.

This might be different the further east in Europe you are - I imagine that someone living in, for instance, Venice with more extensive trade and diplomatic links with the eastern world, might have a higher chance of meeting an Armenian traveller in their day to day lives, but this isn't my area of expertise so I can't say for certain.