Nobody can agree on the origins of the word falcon. We know for sure that it deviated around in earlier English as faulcon and faucon after coming from the Old French word falcun and Latin falco, But here the split occurs. Is the word a conjugation of the prior Latin word falx, which meant "sickle" or "scythe" (a kind of curved sword; this origin describes the talons of the bird), or is it from Frankish falko, which meant "falcon" and "hawk"? Falx, which may be more likely because Latin words normally don't come from Germania, may be Etruscan or from another non-IE family, but it retains the definition as we go back in time. Falko, which may be correct because of its phonemic and morphemic similarities (but it could be related, not the source), would come from Proto-Germanic falko, from Proto-Indo-European poi, which meant "pale", supposedly describing the plumage of the birds. We won't find out which meaning it is for sure unless philologists spend a really long time looking at hard-to-find records, and (sadly) it's likely they won't bother.
Adam Aleksic, a rising sophomore studying linguistics and government at Harvard University, has been described as the internet's sixth most famous etymologist. He also has disturbing interests in politics, vexillology, geography, board games, conlanging, and law.