Brass Knuckles are illegal. Would a glove with a metal plate in between the cloth be illegal too?
An improvised weapon is still a weapon in the eyes of the law. Assault with a weapon is invariably more serious a charge than assault without. Even in self-defense, use of a weapon always makes a situation much more serious legally and you will be required to demonstrate good reason to have had the weapon and just cause to have used it. Since you had to load the glove before you got in a fight, and a loaded glove has no other use beyond hitting someone, that would be evidence of premeditation. A suggestion of premeditation makes it much harder to claim self-defense, since it can seem that you were looking for trouble to use your weapon. The fact that it’s not technically a weapon as such is irrelevant. If I carry a golf club around and hit someone with it, it becomes a weapon, and if I wasn’t playing golf that day it suggests I was looking for a fight as an excuse to use it. Hell, if I buy a frozen chicken for the purpose of bashing someone over the head with it, I’m carrying a weapon
