Eigi skelfr hann

> Before the world-tree goes up in flames, perhaps
> it is time to take a look at the central problem
> here, and settle things once and for all.

I don't think the central problem, if indeed we
have one, is the the genitive form of the name Heiðr.

> Given (a) that there is a certain female named Heiðr,
> and (b) that "hrönn" means "wave", can the phrase
> "hrönn Heiðrs" mean "wave of (the woman) Heiðr"?

Anyone who doesn't know and is actually interested
in knowing can look up the declension of 'heiðr';
here for example:

http://www.midhnottsol.org/zoega/536.html

(It's at the bottom of the page, third declension from the left.
We are fortunate enough that Zoega chose this very word to
exemplify its declension pattern.)

Haukur