Ærið = oerit, the neuter of 'oerinn' "sufficient" (as Zoega spells
it) used here as an adverb, "sufficiently", "enough".

Ærið fögur er mær sjá...
Oerit fögr er mær sjá...
"This girl is beautiful enough..."

> að engir þóttu löglegir dómar dæmdir nema hann væri við.

engir dómar "no judgements", masculine nominative plural of 'dómr'

þóttu "were considered", 3rd person past plural of 'þykkja' "to
seem, to be thought"

löglegir dæmdir (older: doemðir) "legally judged"

nema hann væri við "unless he was present" (i.e. involved)

Magnús Magnússon and Hermann Pálsson have: "He was also a very
experienced lawyer -- so skillful indeed that no judgement was held
to be valid unless he had taken part in it."

Llama Nom