Hm, I'm going to say it's was a combo of Old English
freo/
frið "freeborn" and Germanic
war "guard". (Such language meldings were rather uncommon, but certainly not unheard of.)
I'm not entirely certain of these elements, but I think the above's a good educated guess.
Incidentally,
Hrothgar's just a form of
Roger.
Miranda
Proud adopter of 15 punctuation marks; see my profile for their names.