>>>> fa sret[h] sinni ar sás
>>>> we were a following in which he was satisfied.
> Literally "in regards to which he was satidfied".
> I took 'ar sás' in line (d) to be parallel to 'ôr fhâs' in line (b).
> Preposition 'ó' + relative particle + ro = ór
> Preposition 'i' [does not take rel. particle] + ro = ar.
> For Mod Ir. 'ar' in this sense see DIL I 2.70ff.
I don't think that works. Examples such as the cited "áit ar
marbhadh C." (= place that was killed C. = where C. was killed)
are certainly common. But that construction -- as far as I can
tell -- requires a place/location to be named immediately before
the "i + a/ar" (if past tense). Some examples from Keating:
"san *áit* ar thoirling an ga do ling tobar fíor-uisge as"
= where the spear fell...
"do thuiteadh meas na *tíre* i mbíodh an oidche sin"
= the fruit of that land would fall in which he was that
night (this regarding the result of a false judgment)
My other problem with "ar sás" as "in regards to which he was
satisfied" is that "sásaid" is a transitive verb: "satisfies",
not "finds satisfaction, is satisfied".
(Incidentally, in today's Irish "ar" is just the indirect
relative of "is" and there is no feeling among speakers
that it contains a swallowed "i" in phrases such as "Teamhar,
áit ar cuireadh na ríthe" = Tara, where the kings were buried.
I could be mistaken on this point, but that's my sense of it.)