Hamrammur

Okay, I don't know a lick of Old Norse, but I love the sagas and read
them frequently (in English). I am a fantasy writer, and I named one
of my characters Hamrammir (plural of Hamrammur, I believe). I
understand this word is supposed to be a warrior who can turn into a
bear. Any background info on this word would be greatly appreciated.

Thanks!

--Brady Boyd