With regard to "Horns" on helmets...there ARE some helmets with horns still existing..but they are from the Bronze Age in Europe. About 2000 years BEFORE the viking period. Thet were dicscoverd arounf the time folks statred taking an interest in past history and folks got the idea they were viking. The ones they found were thin bronze, relatively undamaged..so the theory is they were just ceremonial "status" symbols. They weren't 'practical' fighting helmets. You get a good downwards blow on the horns..and unless they were very loosely attached..the leverage would probably break your neck as some-one ponted out