: Nonetheless I am sometimes tempted to invite Martin Read and other medievalists to help put together a FAQ identifying the elements in Middle-earth which can be attributed (or reasonably attributed, if not authoritatively so) to Tolkien's knowledge of the Middle Ages.

: Most of what is argued over in the Medievalism debates would have to be excluded. The armor and weapons, for instance, are not medieval because they go back many centuries before the medieval period. Of course, we'd have to agree on what we mean by "Middle Ages". I think Martin has stated that he feels the true Medieval period began in the 3rd or 4th century AD, but this is an exceptional (though not entirely unique) opinion. I usually say it applies to the period 500 AD through 1500 AD, but I know from the difficulty we had in defining the charter for soc.history.ancient that this is a purely arbitrary definition is by no means used by a majority of medievalists (we had to define a terminating boundary for the group's charter).

: Something that I think could be included would be, for instance, the manner in which Celeborn and Galadriel greeted their guests. I don't know of similar customs from ancient sources, although Homer would probably need to be studied. There are far more classical authors than Homer available, but Greek politics and government started getting more sophisticated within a couple of centuries after his death.

: The custom concerning the Lembas may be identifiably Medieval. Christopher Tolkien, at least, associates one of the Elven names with an Anglo-Saxon term ("bread giver") which eventually became the word "lord".

: Earendil's star is another Medievalism.

: The Rohirrim's stirrups are Medieval, but very little else of their culture comes from so late a period. Their arms and armor bear strong resemblances to the Roman Cibinarii and a few earlier mail-clad lancer types. Their culture in some ways resemble that of the Goths, although some people argue the Goths have been misrepresnted or misreconstructed.

No, not some people- modern historians. However, the Rohir are very similar to the perception held in Tolkien's time of the Goths (and I am willing to discuss the nature of the Gothic culture/people with anyone).
NT
: Theoden's burial strongly resembles a wagon-burial and similar ancient customs of the prehistoric Germans and Celts (whose burial mounds in some places predate the Roman empire).

: The Shire is based largely on rural England of the modern Age (different people give different centuries). And so on. Most of the well-documented aspects of Middle-earth are easily shown not to be modelled on anything from Medieval Europe.