It is of the first declension, but not of the most typical kind.
I would divide the first declension into four classes:
NOM -a -ās -ē -ēs
ACC -am -am/-ān -ēn -ēn
GEN -ae -ae -ēs -ae
DAT -ae -ae -ae -ae
ABL -ā -ā -ē -ē
VOC -a -ā -ē -ē
The last three classes are reserved (almost completely) for Greek names....
It is generally believed is that
"The Italic "1st declension" continues PIE feminine formations ("ā-stems") built with an invariable suffix *-eh2(-)" (Vine 2017: 755)
cf. Beekes 2011 proposal of an ablauting suffix *eh2(-) ~ *-h2(-)).
Weiss notes that
"Masculine nouns of the first declension that we find in Latin are largely personalizations of ...
According to the conclusion of one discussion, constructions in which these nouns are modified by feminine adjectives, when referring to females, are
not so much avoided as simply not needed ... There is no grammatical reason not to treat these as common gender or epicene nouns. There are adjectives in the same declension class, like ruricola and indigena,...
I am a Dominican friar; in our priory in Olomouc in Czech Republic we pray parts of the Liturgy of the Hours in Latin. Brothers most fluent in Latin pronounce all the lengths mostly correctly, others (including me) try to pronounce them making many mistakes. Since our native language distinguishes long and short vowels, pronouncing everything short sound bit ...
Leumann (p. 421) mentions two cases:
spoken gen.pl. drachmum and amphorum;
in dactylic poetry, four-syllable masculine nouns, besides the regular forms, could also have gen.pl. in -um, mostly compounds with -cola and -gena (e.g. agricolum in Lucr. 4.586 or caelicolum; Troiugenum), and some Greek proper nouns (Gangaridum, Aeneadum, Phaselitum).
Actually Du Cange (Glossarium mediae et infimae latinitatis) records a lot of examples of the neuter form Pascha, -ae, which he seems to prefer.
"Orat. et prec. de Pascha annotino"
"Micrologus de Eccles. observ. cap. 56 : Romani Annotinum Pascha,
quasi anniversarium Pascha dicunt, quia antiquitus apud illos qui
in priori Pascha baptizati ...
I don't know about the Vatican. But I've met very few people at conventicula, living-Latin events, etc., who make any distinction whatsoever. I don't generally have a problem, I think in part because nobody talks in insane periods like Cicero uses for orations, and with many speakers, unfortunately, though by no means a majority, word order is closer to ...
I'll give you a partial answer, but I'm not a fluent reader yet, so others will be better able to say.
If the structure is complex enough that I have to "work it out," then it's sort of moot. But, as I've grown more experienced, the complexity of sentences I've been able to "just read" has slowly increased. And when I'm "just reading," it seems I'm able to ...
There doesn't seem to be any single rule that can be used to determine without fail if a first-declension feminine noun ends in ᾰ or ᾱ just from the unaccented spelling of the nominative singular. (I would recommend learning the accented spelling of words, though, since it seems like something that you should know for other reasons.)There are apparently ...
Never realized that, but you have an example (nominative-only, though) in ecclesiastical Latin in the hymn Lauda Sion:
In hac mensa novi Regis
Novum Pascha novae legis
Phase vetus terminat
On this table of the [new] King,
Our new Paschal offering
Brings to end the olden rite.
So I did the exercise and searched for ...
I don't see any reference to such an ending in either Allen and Greenough or Gildersleeve and Lodge, so I strongly suspect the answer is no.
That said, in another, historical sense the -ī ending was used as a first-declension gen. sg. ending, and not just for masculines. The ending -ae is historically formed from -a-ī: the -a- of the first-declension stem ...
I had a Latin teacher who insisted that the long a at the end of ablatives of first declension nouns be pronounced for a noticeably longer time than other vowels. This was the only long vowel she insisted upon and she made a point of it, not only telling us that it was significant, but requiring a very exaggerated lengthening. I'm not qualified to have an ...
In contemporary spoken Latin in Finnish all vowel quantities are carefully articulated.
There is nothing special about the first declension ablative.
I have therefore learned to expect it, and it will be easy to confuse me by ignoring vowel lengths in pronunciation.
The Latin news broadcast Nuntii Latini is a prime example of Latin spoken in Finland, but it ...
I just found that Nouvelle méthode pour apprendre facilement la langue latine, by Claude Lancelot (? et al?), which I quoted in my previous question about Pascha, includes this word in a list of "those nouns which, as grammarians say, are not used in the plural, though we sometimes meet with examples to the contrary" (p. 150, A New Method of ...
Here are all the references that I have found so far that have relevant information about the declension of nouns ending in -es that come from Greek. These references don't specifically mention Arsaces and Gotarzes.
Allen and Greenough:
Many Greek nouns vary among the 1st, the 2nd, and the 3rd declensions.
Boōtae (genitive of Boōtēs, -is),
Sort of, but technically "no".
It seems that -i was sometimes used as a genitive singular ending for masculine names from Greek that end in -ēs in the nominative. But although many of these come from Greek first-declension nouns, they typically seem to be classified as third-declension rather than first-declension nouns in the context of Latin.