The sword I'm talking about is about 7 human heads tall.
In the lore the sword is magical or at least thought to be magical. It is swung around by a creature capable of going invisible, which gives the impression of the sword flying around as if it was possessed by a ghost.
The sword does still have "something magical" to it. The pommel (the round appendix at the end of the handle) is actually a metallic golem's heart/stomach that connects to the "core" of the blade. When the blade strikes something, the heart/stomach is able to absorb minerals and repair the wear and tear of the blade.
It can also protect the user by covering his skin with hard mineral scales that can be detached after a while without much pain or trouble, although they do leave severe scars.
The blade is already humongous by itself and thus really heavy, both due to the sheer amount of material and the leverages, but it also makes the user heavier by covering their skin in scales.
It is supposed to be a slow weapon in my game, mostly for "berserk/suicidal tank" kind of play-styles, or for players who just want to smash things down without thinking much about their safety. In the game, one basically gains "defense points" by striking things with this sword. Defense points reduce the damage the player receives from external factors.
Given those "magical" properties, would the blade be useless and unusable due to its sheer weight, or can I somehow make it usable?
I tried playing with a big tree trunk as if it was a sword, very heavy and very hard to grip but only due to the shape of the tree, it was mostly like swinging around a mace rather than a sword though. Seemed very impractical from my experiment, yet the blade is made of more dense materials thus probably heavier than the tree trunk.
A good answer should apply the in-game sword's "magic" to real life, handwaving away the magic and only thinking about the practical usability of the sword.
The scales form instantly, so ignore the physics of how fast they are created, given that they probably would explode or something like that if they were made at that speed.