Neil wrote:

>>> (a) a dil DonnchADHA Gairbh
>>> (b) grian n, f(h)ine or [= ar] fhs
>>> (c) bech as grinne gaos
>>> (d) fa sret[h] sinni ar ss
>>> Dear grandson of Donnchadh Garbh
>> fiery sun of a family from which has grown
>> a bee of keenest wisdom
> we were a following in which he was satisfied.

"Fa" = "ba", right?  "fa sreth sinni" = lit. we were a rank

DIL points to a somewhat mysterious idiom, clearly late,
at S 63.18, exemplified by this half-stanza:

atm ar ss luit  Fhloind;
fan cruit do fhs in fhochainn.

I translate this as:

we are prepared to destroy  Floinn;
the cause (of war) grew over a harp.

Does that make sense, and if so, can we take "ar ss" to mean
"prepared, ready" in our poem?

fa sret[h] sinni ar ss = we were a (well-)prepared rank