the last syllable NEVER receives the stress.
I think it is, as you suggest, to distinguish the singular ablative of the 1st declension from the singular nominative (sometimes a thorny interpretive problem). I highly doubt that it was ever used to mark stress, since stress in Latin is not arbitrary but rather dependent on regular rules. As long as you know the quantity of a word's vowels, you can determine its accent.
I think that 16th and 17th century authorities should be listened to
not so much in classical times, but as it was, or was recommended to be, spoken in their own day.
NOTE.--The Romans sometimes marked vowel length by a stroke above the letter (called an apex), as ^ ; and sometimes the vowel was doubled to indicate length
Lucus Eques wrote:As for pÃ¡cem, that makes more sense, at least as far as Greek accentuation rules go, whereas pÃ¢ce makes sence in the ablative.
Hu wrote:There's an excellent guide to Greek accentuation here.
adrianus wrote:Dear Luci (or is it Luce?--in a seventeenth century source, I see that the vocative for Lucus can be both Luce and Lucus, and Luci the vocative for Lucius),
I think this stuff may be quite novel so I'm preparing a paper on it and I can email you the paper for your comments when it's ready (if you would like that). It worries me, of course, that I'm very wrong and exposing my considerable ignorance, or else I'm right but it's all a commonplace. I promise to post some examples asap (certainly within 24 hours), but what I'm doing immediately is gathering evidence from sources and devising a method for its analysis.