Ok, @Horemvore: You were right and I was wrong. My apologies.

Eikthyr DOES follow you everywhere. I did this several times with the Elder where it WORKED.

Apparently it does not with Eikthyr.

That is a bummer, and I would, as @Aimee suggested, use another world to recreate the equipment required, get back to your old world when properly prepared and make mincemeat out of 9V-Bambi.

And yes, you can kill him with lvl 1 deer leather pants, lvl 1 rag tunic, and a lvl 1 crude bow with wood arrows. And a lvl 4 flint knife. Food was deer, raspberry, honey.

I had no rested bonus, as would've the OP when they would freshly log back in to their world.

I still not suggest the OP does it that way, as it requires some knowledge of the game.