We got a little pickle here, you are either in error, or it was a slightly more complated issue.
Frostband is a shaman elemental combat spell, In general they cast it on themselves and recive the effects for 5 min, then it wheres off, the issue, Shaman cannot use Sowards, so the forstbad was either on a diffrent weapon, or said shaman has a strange totem I was not allowd to train that gives his partymates frostbrand(this part is a joke, they dont have said totem)
Short awnser, it is a class skill, cant get it unless your a shaman.....