> Gerðu honum skyrtu og brautgangs höfuðsmátt og seg skilið
> við hann fyrir þessar sakir."

> Make him a shirt and the-opening-for-the-head
> grounds-for-divorce and say to part with him over these
> charges."

> Make him a shirt and cut-away head opening and say you
> divorce him for that’s sake.”

> Make(-you) him a kirtle and an opening-for-the head
> (collar) of departure (lit: going away,possibly (1)
> departure from what is acceptable, (2) grounds for
> divorce/separation, or (3) going away from the neck, ie
> revealing, off the shoulder, with plunging neckline?) and
> declare the separation with (ie declare yourself divorced
> from, see segja, Z3) him for these reasons.“

I'm pretty sure that it's 'divorce's neckline', i.e., one
that's grounds for divorce. Apparently men wore high
necklines, while women's necklines were much lower, and
wearing clothing appropriate to the opposite sex was grounds
for divorce. The bit at the end of this passage appears to
be the same sort of thing, but with the sexes reversed.

> Það sama vor seldi Ingunn land sitt í Króksfirði, það sem
> síðan heitir á Ingunnarstöðum, og fór vestur á Skálmarnes.

> That same spring Ingunn sold her land in Hook-inlet, that
> which then is called Ingunnar's place, and went west to
> Skalmarnes (Eagle-prong?).

> That same spring, Ingunn sold her land in Krok’s firth,
> that which is previously called Ingunn’s steads, and went
> west to Skalmar Ness.

> That same spring, Ingunn sold his land in Króksfjörðr,
> that which later-on is-called (at) Ingunnarstaðir
> (Ingunn‘s-steads), and journeyed west to Skálmarnes
> (Prong‘s-Ness).

I would say 'which has been called (at) Ingunnarstaðir ever
since' or, if a more literal version is wanted, 'which ever
since is called ...'.

> Þeirra synir voru þeir Hallbjörn slíkisteinsauga og
> Stígandi.

> Their sons were Hallbjorn "those stone eyes" and Stigandi.

> Their sons were they, Hallbjorn whet-stone’s eye and
> Stigandi.

> Their sons were they: Hlallbjörn sleek (?)-stone-eye and
> Stígandi.

According to CV, a <slíkisteinn> is a 'smooth-stone', i.e.,
a fine whetstone. There is a Nynorsk verb <slikje> 'to be
smooth and shining/glistening; to make flat and smooth, to
stroke, to polish', evidently from the base; possibly the
idea is that H's eyes looked like smooth, glistening stone.
In our terms that would certainly be appropriate for an
unpleasant character.

> Þá mælti Guðrún: "Hvort er það satt Þórður að Auður kona
> þín er jafnan í brókum og setgeiri í en vafið spjörum mjög
> í skúa niður?"

> Then Gudrun said: "Are you satisfied, Thord, that your
> wife Audr is always in pants and seat-gore wrapped up (?)
> many garments down to shoes (?)?" (According to one
> dictionary, "gore" can mean a piece of fabric, for
> whatever that's worth.)

Specifically, a gore is a triangular piece of fabric used to
give a fabric construct (garment, sail, etc.) a desired
shape. It's also a small triangular piece of land,
typically a leftover bit between larger rectangular plots;
indeed, this is the earlier meaning (Old English <gāra>
'corner, point of land', akin to OE <gār> 'a spear').

> Then Gudrun spoke, “Is it true, Thord, that Aud, your
> wife, is always in pants and seat-gores and wrapped
> leg-bands well down into (her) shoes?”

> Then spoke Guðrún: “Is that true (sannr), Þorðr, that Auðr
> your wife is always in (ie wearing) breaches and (with)
> seat-gore in (them) but the wrapping (vaf, noun + def art)
> with leg-bands almost (mjök, Z3) down into (the) shoes (pl
> of skór)?”


> Guðrún svarar: "Hitt skiptir hana enn meira að hún eigi
> þetta nafn lengi síðan."

> Gudrun answers: " [Hitt skiptir???] to her still to me
> that she had this name long since."

> Gudrun answers, “It ?? her still more that she has this
> name longer afterwards.”

> Guðrún answers: “That concerns (see skipta Z3) her still
> more that she has (keeps) this name for-a-long-time
> afterwards.”

(I believe that you mean Z4.) <Eigi> is a subjunctive, so
I'm inclined to read <að> as introducing a conditional: 'if
she keeps this name for a long time afterwards'.

Brian