Heil Arlie!

> At any rate, we have:
> Maðr er nefndr Grímr kamban;
> A man was called Grímr kamban. What could be simpler? Well, yes, it's a
> name, and I recognize it as a name. But where did the -an ending come
> from? That looks like an accusative masculine adjective ending.

Good observation. It isn't an inflectional ending, though.
The name is thought to be of Irish origin (Cammán) and 'an'
can be considered a part of the stem.

Kveðja,
Haukur