Heil!

> The word 'asniligamo' cropped up on another site, apparently Old West
> Norse, and I have since been trying to find a translation.

Doesn't make any sense to me. There is indeed a word
'asni' meaning 'ass' but 'ligamo' doesn't look like an
Old Norse word. If the 'o' ending is really an 'o' ending
then why hasn't the 'a' mutated? It would have to be long:

ligámo?

If we split that again then 'ámo / ámu' is recognizable
as a form of 'áma; barrel' but 'lig' is not familiar.

How about amending one letter?

'asnalig ámu'

ass-like [nominative singular feminine] barrel [oblique case singular]

Fond as I am of chasing wild geese I suggest you find the
word's context, if any there is, and get back to us.

Kveðja,
Haukur