Here is my translation.

Alan

Tókst þá bardagi ok stóð hann með mikilli mannhættu. 
Then a battle took place and it (ie the battle, masc) stood with (ie involved) great danger-of-life (lit: person(al)-danger).

Sigrgarðr réð tvísvar til uppgöngu, en Jógrímr skít-í-andliti varði svá sterkliga stafnin at hann stakk hann hvártveggja sinni aptr á sitt skip. 
Sigrgarðr twice commenced (attempted, ráða til e-s) a ship-boarding (lit: up-going), but (and) Jógrímr shit-in-countenance (“Shit-face”) defended so strongly the stem (of the ship) that he drove him (Sigrgarðr) each time (of the two) back to his ship.

Velstígandi kom þá at, ok krækti með króksviðunni í kjaptinn á Jógrími, ok kippti honum ór stafninum. 
Velstígandi (Well-Stepping) came then at (him) (ie attacked), and hooked (krækja) with the billhook into the jaw (mouth) of Jógrímr, and pulled him out-of the-stem (of the ship)

Sigrgarðr var þá nærri staddr ok hjó á háls Jógrími ok tók af höfuðit ok fekk hann þegar bana.
Sigrgarðr was then (ie at that time) stationed near (by) (nærri=nær), and hewed on (the) neck of Jógrímr, and took off the-head, and he (Jógrímr) received at-once (his) death.

9
9.

Þeir Hörðr ok Sigrgarðr hlupu þá báðir senn á skip Knúts, ok gekk með sínu borði hvárr, ok drápu margan mann. 
They, Hörðr and Sigrgarðr then leaped both at-once on-to Knútr’s ship, and each (of the two) went along their-own side (of the ship) (ie they chose one side each to operate in), and killed many a person (man).

Gráboli sneri í móti Herði, ok sló til hans með gaddakylfu, en Hörðr beygði undir kenginn; kom á krippuna ok var fast við ok varð Grábola laus kylfan. 
Gráboli turned to a meeting of (ie to face, confront) Hörðr, and struck at him with a spiked-club, but (and) Hörðr bowed under the-(his) kink (stooped down with his bulging butt sticking up in the air?); (it, the club) came on-to the-bulge and was (ie stuck) fast against (it), and the-club became free of Gráboli (ie Gráboli was forced to let go of the club).

Þá veifði Gráboli hornunum, ok vildi stinga Hörð með því horninu sem ór enninu stóð. 
Then Gráboli waved (wagged, shook?) the (his) horns, and wanted to stab Hörðr with that-one, the-horn which stood out-of the-forehead

Hörðr greip í hornit svá at brotnaði af honum. 
Hörðr grabbed-hold of the-horn so that (it) was-broken off him.

Gráboli vildi þá ljósta hann með því horninu sem ór vanganum stóð, en hann brá við stjelnum. 
Gráboli wanted then to strike him with that-one, the-horn which stood out-of the-upper-cheek, but (and) he warded it off with (bregða við e-u) the-(his) hinder-part (ie his backside, butt)

Hornit sökk allt upp at hausinum. 
The-horn sank (in) completely up to the-(ie Gráboli’s) skull (ie the full length of the horn was completely lodged within Hörðr’s butt).

Hörðr vingsaði dausnum, ok vatt Grábola fyrir borð. 
Hörðr swung-around the-(his) rump, and twisted Gráboli over-board.

Gráboli kipti honum fyrir borð með sér. 
Gráboli pulled him over-board with himself.

Stígandi sá þat ok stökk fyrir borð ok krækti krókshyrnunni undir kjálkann á Grábola. 
Stígandi ((Well)-Stepping) saw that and sprang over-board and hooked the hooked-point (of the billhook) under the-jaw of Gráboli.

Ei tók Stíganda meir sjórinn enn jafngegnt vörpum. 
The-sea took (ie reached) not for Stígandi more than just-opposite (the) stitched-edge-of-(his)-shoes (varp)

Hann tók þá snæri ok renndi at hálsi Grábola, ok hengdi hann við kollarðinn á skipi sínu, en dró Hörð upp í skipit. 
He took then a twisted-rope and ran (the loop) around (the) neck of Gráboli, and hanged him by the head-plough (kollr + arðr ?) on his ship, but (and) drew Hörðr up into the-ship.

Gengu þeir nú á skip Knúts ok ruddust um fast.
They went now on-to Knútr’s ship and cleared-their-way fiercely.