This etymological puzzle is starting to consume my daily thoughts. The Etruscan name for Arretium, as I mentioned earlier, appears to be Aritim, at least according to Steinbauer. I now think he's correct. However, if this is so, any distinctly Etruscan connection that Pallottino had claimed existed between the Roman urbonym Arretium and the modern German word for 'ore', Erz, is smashed. Yet there are more nagging details about these etymologies that I just don't find convincing.
For example, the claim that the Germanic words for 'ore' derive from Arretium seems like the reverse of what I personally would deduce from the evidence. It's the Germanic terms that are shorter than the name from which they purportedly derive, afterall, and this is mightily suspect to me. One would almost reckon instead that the name of Arretium derived from the Germanic words for 'ore'. And why not? It seems to me that Etruscologists are obsessed with the thought that Arretium must have been founded by Etruscans. Yet beyond the fact that the city was Etruscan from the most ancient historical times, what evidence exists that the Etruscans also established it in prehistory as opposed to taking it over from indigenous peoples like the Italic or Germanic population? All I see so far is a city positioned remotely in the interior of Italy in the northernmost region of Etruria that by all accounts has been shaped from the earliest times by not only Etruscans, but Italic-speaking and Germanic-speaking populations as well.
So I was thinking the other day, “What if 'Arretium' was originally a Germanic name?” It's a delicious thought that I can't pass up. I'm tempted to posit a form like *Arutjōn signifying 'Ore Town' (< *arutja- 'ore' plus derivational suffix *-ōn as in *bijōn- 'bee'). The city was known for its bronze and so such a name would be apt. From there, Latin-speaking people could have assimilated the name as Arretium very easily. The Etruscans would in turn have borrowed it directly from the Latin speakers, as indicated by the word-final -m. Aritim is not an analysable name in Etruscan terms, so I'm entirely convinced that it's a foreign name one way or another and that regardless of the Etruscan political history of this town, the whole thing is making me believe that the cultural mix of Arretium in prehistoric times was much more complex than currently appreciated.
 Steinbauer, "Zur Grabinschrif der Larthi Cilnei aus Aritim/Arretium/Arezzo", Zeitschrift für Papyrologie und Epigraphik 121 (1998), p.263–281 (see pdf).