samsaw an interesting theory about viking swords last year which I will share with you all
probably the two most distinctive (and consistent) features of the classic viking sword are the slow tapering of the blade and the wide, heavy pommel.
(the above are technically type Xs but they are close enough to the Viking blade for illustrative purposes)
the slow tapering of the blade (and thus relatively even weight distribution) meant the balance of the sword is relatively high (only somewhat counterbalanced by the wide heavy pommel).
this is somewhat in contract to more evenly tapering swords, which taper to keep the balance point towards the grip, making the sword more manageable.
why is this important? well! the theory goes: the sword was not meant to manipulated precisely like later european swords, but to be swung more like an axe or mace! the weight being higher significantly increases the torque.
the wide pommel, on the other hand, locks the sword into your palm, allowing it to pivot without flying out as you let the sword's weight do the work.
(the attached gif is from https://youtu.be/IqnSllg0TXM)
Viking Age Swords Compared to Later Medieval Ones
anyway! afaik this is just a theory, so take this all with a grain of salt! the video I linked has lots more footage of a man swinging a viking sword around if you're interested. thank you for coming to my TED talk.