Up to now i realized that, not only Europeans but all those who have travelled around the world, had to catch the sound and eventually write about the name of things they met, using their own alphabet; one may imagine arabic speakers, such great travellers, having to convert into their script whatever objects they heard being named by locals. One even has to consider how such names, once being perpetuated by strangers, were result of the perception of simple people or of intelectuals; it is perhaps pertinent to admit that, the name of a sword perceived by illiterate navigator crewmen might be distinct from that picked by one such Ibn Batuta.
Also we may consider that, the earliest the etymon is, the more corrupted it may have been.
And then we have the optional (different) name peoples use to address the same thing, depending on the area of the country where they reside; all of them good, as consuetudinary.
On the other hand and introspecting into the Western side of things, if we pick the consensual 'knife' term, when consulting the Oxford dictionary, the description includes a couple encrypted symbols, linked to Old english after Old teutonic but, for what is worth, it ends up assuming that, the root of the word is of uncertain etymology.
In any case the object called 'knife', as other, when used in other languages may not be a strict 'transfer' of the term to local composition, but one of different provenance.
Spaniards use 'cuchillo' and French use 'coucteau', both appearing to have a more traceable identification, with direct connection to latin 'culltellus'.
Whereas the term selected by Portuguese, 'faca', appears to have incognito parents. Latin 'falcula' being rejected, as well 'falx'; the arab "farkha" offers no plausibilty, as intrinsically appointing to a completely different direction. It is consensually a term certainly introduced by populars, admitedly pre-Roman, and of obscure origin.
Definitely, life of scholars/academics is not easy, having to deal with all these endless riddles; but there are so many living humans out there that, of those, many are that chose to struggle with such problematic tasks. Much easier for those that are pleased by understanding eachother with whatever means; and, in case spoken resources fail ... we can always resort to sign language
All in all, discussing the nuances of terminology is not counter-productive nor unwarranted; it is imposing their revision that has no sense, instead.