I find on the contrary «
notre vie, douceur et espoir » “weirder” -or rather more surprising to read or to hear- than «
nos vie, douceur et espoir », albeit I understand that a stylistic ellipsis is made in the first (which is what makes it weird or surprising... intentionally if it is a literary style, or not if it is an oversight), while the second is classically constructed, with the adjective agreeing with the nouns, which is the logical rule.
Grevisse writes “
Dans le cas, relativement rare, où un seul déterminant sert pour plusieurs noms, l'accord se fait comme pour l'épithète : le déterminant se met d'ordinaire au pluriel ; le genre est celui des noms, si ceux-ci ont le même genre ; sinon le déterminant est au masculin”. Grevisse gives two examples, among whom our parental one:
tes père et mère honoreras (traditional version of the Decalogue).
Grevisse gives also:
Les enfants doivent des aliments à leurs père et mère (Code civil, art. 205) ;
les gendres et belles-filles doivent également [...] des aliments à leurs beau-père et belle-mère (ib., art. 205).
However, the ellipsis is occasionally used in the literary register and is commonly used in the juridical register. Grevisse gives, as an example:
J'ay tiré autrefois usage de nostre esloingnement et commodité (Montaigne, III, 9), with an ellipsis of [
de nostre] before the second noun.
The ellipsis also commonly appears in set phrases, especially when the nouns are synonymous. Grevisse reports that
aux lieu et place de... and
en ses lieu et place are found in Ch. de Gaulle,
Mémoires de guerre; J. Delay,
Avant mémoire), M. Tournier,
Météores, R. Pernoud,
Jeanne d'Arc, M. Leiris,
Langage tangage, but also gives
en son lieu et place (art. 1684 of the Civil code), but
en ses lieu et place (art. 385 of that same code).
Another (very common) example of an ellipsis given by Grevisse for quasi-synonymous nouns:
En mon âme et conscience.
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By the way, you are right that the two phrases,
vie, douceur et espoir and
père et mère are not equivalent, I agree and I was well conscient of that, but it is difficult to make a representative search with things that doesn't commonly come in pairs nor with possessive.
I've just checked, following that comment:
«
notre vie, notre douceur et notre espoir » : 14 online results.
«
nos vie, douceur et espoir » and «
notre vie, douceur et espoir » : no online results.
There's also the fact that "vie, douceur et espoir" are embodied in a single individual here. So maybe modifying them with a plural adjective makes them feel too separate and that's part of why it sounds wrong.
The second example gave by Grevisse is
on lui a demandé ses nom, prénoms et qualités, which, here also, are elements embodied in a single individual.
However, there is this element, which is connexe to your message, albeit different (it doesn't apply for
vie, douceur et espoir who are clearly distinct concepts): “
si les noms désignent un seul être ou objet : [...] mon seigneur et maître”. And indeed, I think that
mes seigneur et maître to name one unique man, who is both the lord and the master of the speaker would sounds a bit odd.
Grevisse also gives:
En deuil de leur fils et frère bien-aimé, Fernand (Yourcenar,
Souvenirs pieux). Fernand being both the son of his parents and the brother of his siblings.
