I too would like learn where people can learn wrong art of the power of psychokinesis or have the wrist strength to be able to balance 3 longswords in the palm of one's hand
Joking aside, good form makes the blade effective, even more than the danger the blade presents itself
Swords that're meant to be able to be held with that kind of grip usually have an unsharpened bit for that purpose. Alternatively, if you're armored from head-to-toe, just make sure your gauntlets are on tight.
I suppose the point of a longsword is less "wickedly sharp razor blade to slice and dice with precision" and more "wedge shaped heavy piece of metal to drop on people with the hope of finding a gap in their armour"
Swords historically have a ricasso. That’s the base part of the blade, and it generally isn’t sharpened, specifically to be able to use half-swording (having one hand on the grip and one on the blade). The hand on the blade is often at like 1/3 of the blade tho. It was used to stab into weak points of an armor with precision (since swords were pretty bad against armored foes).
But also, half-swording is done by "pinching" the flat of the blade betweend the palm and the fingertips, in a way that prevents touching the sharpened thread. It isn’t shown on this (very historically accurate, if i may say so) image
You could cut yourself if you're not carefull, but if you do it the right way you don't risk that much.
The proper way to grab the blade of your sword, be it for half-swording as shown in the meme or to go for a mordslag, would be to put the bottom of your palm on the flat of the blade, and then wrap your fingers around the edge without touching, and holding the other side of the blade with just your fingertips. This way there is actually a space between the edge, and your hand.
You could even test this method with a kitchen knife if you want to. You'll be surprised by how actually stable this grip is.
Additionaly, even in case of "naked" combat, people often uses leather gloves which do in fact provide a fair bit of protection against accidental cuts.
That buckler, however, is not being held correctly. You hold it as far out in front of you as possible with a stiff arm. You don't sweep blows away like in dark souls.