> Noticing that MM &HP choose Quarter for the word Fjorðungi seems

good for fjorðing is literally "fourthing" and we once had the
"farthing" a coin worth one quarter of a Penny when there were 240 of
Pennies to a Pound - I have often wondered how much of our English
has directly descended from Old Norse

The OED says Old English 'féorðing', 'féorðung', the ancestor or our
'farthing', "may possible" be from Old Norse; or it might be a
parallel native formation. First attested in English c. 950 in the
Lindisfarne Gospels.