Hopefully someone else can weigh in on how widespread this glima was, it sounds interesting.

But I would like to drop this link in relation to the first part of the question: https://www.reddit.com/r/AskHistorians/comments/gb1azr/comment/fp4ock5/

In it, u/BRIStoneman examines the track record of the vikings in battle (specifically in England) and argues that when it comes to fighting... they generally lost. What they were good at was seamanship and seafaring, allowing them to strike where their enemies weren't, so they could prey on civilian populations who couldn't fight back.