@Me
Longbows and crossbows weren't what killed knights.
Firearms were. Because bows require strength and dexterity, crossbows strength (though later could be reloaded with a handle) and precision in loading... firearms required no strength or training past "how to clean and reload your gun". They also obscured vision, creating chaos on the field, making it harder for charging infantry or even cavalry.
That's when people finally had to leave heavy armors at home, in favor of something cheaper and more mobile - if your soldiers are gonna die anyway, might as well lose as little resources as possible. And maybe they'll kill someone before they bleed to death if they have less armor to carry around.
@Raknasuu
Half-swording is any move that has you grab the blade with your (ideally armored) glove and use it to stab at enemy or push with both hands for more pressure. What you're thinking of is a specific kind of half-swording, mordhau, to use the pommel as blunt weapon.