Ulfberht?
The only thing bad about Viking swords are their small grips. They don’t allow for much in the way of freedom in the hand later swords hand.
The a-typical medieval long sword had a nice long handle for leverage and more fluid motion in the hand to allow a greater more comfortable range of motion by the user. Where as the viking swords, too my knowledge, lacked that for the most part.
Of course, the thing to note about European swords is that Europe changes so much in its doctrine throughout its history swords had to change a lot to keep up too. So you get a wider amount of experimentation and adaptation from long-sword to broadsword, and then phasing those out in favor of the rapier, and then swords all together become obsolete when we start shooting guns at people and stand in Napoleonic/Semi-Napoleonic lines until just before the First World War.
Japan on the other hand didn’t really change or develop their swords nearly as much it seems. They stuck to one design and one design only. But, the bow and the Yari have always been more the staple of their warriors.
Hell, even China has played around with their concept of the sword. At least until 1911 I think.
