Here’s my translation

Alan

Nú koma þeir á mýrina og þegar hleypur Kýlan upp úr einum runni og sótti að Mávi í ákafa. 
Now they come to the-swamp and immediately Kýlan jumps up out-of a certain bush and attacks Már eagerly.

Askmaður skopar um hið ytra og vildi krækja af honum skjöldinn. 
Askmaðr takes-a-run (skopa, Z2) around the outer (?) and wanted to drag-with-the-hook (of his barbed spear) the-shield from him (ie Már)

Már hjó hart og tíðum en sverðið beit ekki. 
Már hewed hard and often and the sword bit not.

Þá kastar hann skildinum en þreif sverðið báðum höndum. 
Then he casts (off) the-shield and grasped the-sword with both hands.

Hann hjó á öxl Kýlans svo hart að lamdist axlarbeinið og jafnskjótt hjó Kýlan í mót og kom á hendur Mávi og tók af báðar í úlfliðum. 
He hewed onto the-shoulder of Kýlan so hard that the-shoulder-blade (lit: shoulder-bone) was-severely-injured (lemjast, Z2) and immediately Kýlan hewed in return and (it, the blow) came onto (the) hands of Már (which were holding the sword) and took off both at the wrist.

Már rann þá á Kýlan og spennti um hann stúfunum. 
Már ran then at Kýlan and clasped around him with the-stumps (of his arms).

Þá hljóp Askmaður á bak Mávi og lagði á meðal herða honum svo að fram kom í brjóstið. 
Then Askmaðr leapt on to Már’s back and thrust between his shoulders so that (it) came forward into the-(front-of-the)-chest

Þar féll Már, hinn besti drengur, og huldu þeir hræ hans og sögðu Halli hvar komið var. 
There Már fell (in battle), the best man-of-valour, and they hid (covered) his dead-body and said to Hallr how matters stood (kominn, Z) (I also thought that one could read this expression as “where (it, the body) was (had) come”. ie where they had left the body)

Hann lét vel yfir. 
He expressed approval if (it).

Eftir það fóru þeir heim og lagðist Kýlan í rekkju og ónýtti höndina.
After that they journeyed home and Kýlan lay-himself in bed and (it) made-useless the-hand (ie the hand became unfit for use).

Hallvarður var heima er hann frá lát sonar síns. 
Hallvarðr was at home when he was-informed-of (the) loss of his son.

Hann var þá til einkis fær. 
He was then in no way (einskis from engi?) able-to-go (foerr)

Þá sendi hann mann til Þóris að segja honum tíðindi. 
Then he sent a person (man) to Þórir to say to him (the) tidings.

Hann svaraði fá um þetta. 
He answered little (I expected dative, but what case is this?) about this.

En litlu síðar fóru Þórir og Ketilbjörn og Kinnarsynir til Hafrafells og fundu Kýlan í dyrum úti. 
A little later Þórir and Ketilbjörn and (the) sons-of-Kinn (Cheek) journeyed to Hafrafell (He-goats’-fell) and found Kýlan in (the) doorway out (of bed?)

Þeir beiddu bóta fyrir víg Márs en hann svarar illa og rak aftur hurðina í klofa. 
They asked for compensation for (the) slaying of Már but (and) he answers badly (unfavourably) and drove back the-door into (its) groove.

Þeir tóku stokk og brutu upp hurðina og fundu hvergi Kýlan en fundu laundyr á bak húsum. 
They took a log-of-wood and broke open the-door and found Kýlan nowhere but found a secret-doorway at (the) back of (the) farm-buildings (plural).

Hlupu þeir út og sáu að Kýlan var kominn upp í fjall. 
They ran out and saw that Kýlan was (had) come up into the-mountain.

Þeir runnu eftir honum og þar til er vatn varð fyrir þeim. 
They run after him and to there where a lake arose before (in front of) them.

Þar hljóp Kýlan á út en Þórir skaut eftir honum spjótinu því er faðir hans hafði gefið honum og kom í milli herða Kýlan og kom hvorki upp síðan. 
There Kýlan jumped out (of the water?) at (them) but (and) Þórir shot after him the-spear, that which his father had given him and (it) came between (the) shoulders of Kýlan and neither-of-the-two (shoulders?) came up (rose) afterwards.

Eftir það fóru þeir heim.
After that they journeyed home.

Þá ræddi Þórir um að hann vildi finna Askmann. 
Then Þórir spoke about (it) that he wanted to meet Askmaðr.

Og er þeir komu á bæ hans voru aftur hurðir. 
And when they came to his farmstead, (the) doors were shut.

Þar voru lítil hús. 
(A group of) little farm-buildings (plural) were there.

Viðköstur var fyrir dyrum. 
A pile-of-wood was before (the) doorway

Þeir Þórir ruddu viðinum á hurðina og báru eld í. 
They Þórir (and co) tossed the-wood against the-door and bore fire into (it) (ie set it alight)