> og varð það aldrei að þeir fengju færi á honum

"but it never happened that they got a chance to attack him"

'fengju' is the Modern Icelandic past subjunctive 3rd person plural of
'fá' "to get". Before the 15th century, the plural was the same as
the singular: 'fengi'.

'færi' (older 'foeri') is a neuter noun, here meaning "chance" or
opportunity" (to attack).