They never did
No.
Vikings didn't use horned helmets.
They didn't wear horned helmets.
They didn't. Well, at least not in battle. A horned helmet might LOOK good, but the horns would make it real easy to knock the helmet off. And if you had it strapped on tight, a good strike would either knock the horn off, or break your neck. Horned headgear might have been used in rituals for some sort of symbolic value though.
they found it harder to battle with the wieght
Vikings don't have horned helmets.
No the vikings did not have horns on their hats. A artist thought it showed who they were so he gave them horned hats. And ever sense people think that is true. Scientist have proven that that is false.
Click on the 'Vikings Helmet' and 'Vikings Goalpost' links below to find coloring pages of the helmet and goalpost.
There's no evidence that the vikings ever wore horned helmets. For combat gear it'd be kinda silly to create a helmet that's real easy to knock off. That image was most probably created by the movie industry. Sticking something big and pointy on top of a helmet will make the wearer look taller, and probably more ferocious though, so it makes a great stage prop.
No. Vikings did not wear animal horns on their battle helmets. This was a depiction that began with mythic descriptions in 19th century Sweden. Horns may have been part of ritual costumes as in the Teutonic religions.
The Minnesota NFL team is nicknamed the "Vikings". Think of the classic image of a Viking, with the classic horned helmet. The logo on the Vikings' helmets is supposed to look like those horns sticking out. Obviously, trying to do a 2-d drawing of the horns like that leaves a bit to be desired and one has to look at it with a little imagination.
Vikings had a metal helmet with no horns on so any one that told you that they did they are wrong. The idea of the Vikings having horns on there Helmets came from the Victorians