I forgot to mention that because the words occurs
in a poetic stanza, it can be looked up on the
Lexicon Poeticum. If you know a little Danish, you
can find the entry here:
http://www.hi.is/~eybjorn/ugm/lp/ol2.html
If your Danish is less than little, I can help you
out:
"ikke efter skæbnen, unaturlig"
means
"not in accordance with fate/nature/creation,
unnatural"
"Skæbne" (ON sköp) is a complex word, and "fate" is
not a 100% translation of it. This is where the -skap-
in 'óskapligr' originates, but this you already knew,
I'm sure.
Hoped this helped a bit more,
P.