> En að áliðnum degi var henni veittur sá umbúningur sem hún skyldi
til að fremja seiðinn.

> But ?? day was to her to give such equipment as she should (need) to
work the spell.

"But as the day drew to a close..."
"But as it got late in the day..."

'áliðnum' is masculine dative of the past participle of the verb 'líða
á', cf. 'ok er á leið daginn' "when the day was far spent". The
preposition 'at' is used sometime like this with a noun and participle
to indicate something happening when the action of the main clause
takes place, or something that has happened: 'at áliðnum vetri'
"towards the end of winter". For more examples, see Zoega 'líða' and
also 'at' A.III.(3) "used with an absolute dative and present or past
part. at sér lifanda, during his lifetime; [...] at liðnum sex vikum,
after six weeks; at honum ðnduðum, after his death."

> En mér eru nú margir þeir hlutir auðsýnir er áður var bæði eg og
aðrir duldir.

> But to me now are many they parts ?? appear?? where before was both
I and others concealed?

"But now many THINGS are clear which before both I and others were in
ignorance of."

The indeclinable relative pronoun 'er' has the role of the genitive
object of 'duldir' in the subordinate clause. Interesting that
'duldir' is masculine by default.