what does a name have to do with the weapon besides itself? Have you ever held a keyblade before? You sound like that guy on youtube who tried to say the keyblade wouldn't work. Though it's called a keyblade it's used as a blunt weapon; you don't hit with the spiked side/teeth of the key, you hit with the backside. I have obviously made an held several keyblades and they all feel comfortable to hold and swing around as long as you're strong enough, like with a real club.
The unnecessary material IS just decoration based on the world it came from, but that doesn't mean it hinders the weapon. It just adds weight which takes us back to the strength of the user. You also have to look at the fighting styles of the character in the game to better understand some of the designs. The kingdom key for example is used by sora and mickey, one uses two hand (or one and a half hand) grip and the other uses mainly one hand. This keyblade is good for either style because it has more space between the handle and the guard. For two-hand grip, you grab the handle from each side of the guard, and for one handed you grab it from outside the guard, leaving it between your forearm and body. It's very comfortable, and with the teeth facing up in the air like they should be to hit someone with the blunt end, it feel very balanced. However for some reason, criticizers think the teeth go down which makes it feel unbalanced and confused.
I've had this debate several times. It's really getting old to explain it to people. Sure they could have used a different name, but why does it matter if it's creative and catchy for a game.