What this song renders
The death of Haakon the Good at Fitjar is the most concretely-detailed kill in the whole album, and the detail is the saga’s, not the album’s. Heimskringla specifies the valbǫst — a rare or distinguished arrow — striking the king under the arm where the sleeveless mail-byrnie left him open, names the bowman, and follows the dying king north to the rock on the Norwegian coast that still bears his name, Hákonarhella. Haakon won the battle and lost his life; the throne passed to the Eríkssynir, and Gunnhild ruled Norway through her son Harald Greycloak for close to a decade. All of that is in the political record.
What the album adds is the cursing-mother point of view, and even that has a saga footing: Snorri reports, in the ‘men said’ register he uses for things he will not vouch for, that Gunnhild’s seiðr had named the arrow before it flew. The album commits to what the chronicler only repeats — it stages Gunnhild at the loom, naming the arrow, the wound, and the stone, while the men fight a battle she never reaches. This is the distant-causation hero scene the catalogue first ran with Sigrid at Svolder; the difference here is that Gunnhild is emphatically on-camera, acting, rather than absent.
The chorus’s closing line widens with each pass — the field, the shore, the world — tracking the cursing-act from one battle to the whole arc of the Eríkssynir’s reign. The outro withholds the engine and hard-cuts on the thesis the saga leaves implied and the album makes explicit: she did not ride to the field; the arrow went, by her hand.
Documented kill, sagaic cause. The valbǫst, the under-the-arm wound, the bowman, and Haakon’s death at Hákonarhella are all specified in Heimskringla; the battle and the succession are firm political history. That Gunnhild’s seiðr named the arrow is reported by Snorri only as something ‘men said’ — the album promotes that hearsay to its organising claim, which is the witch-queen reading, not the chronicle’s verdict.