Besides, half of those probably couldn't kill a cat--
honestly
Try duct taping a sharp jaggy rock to a long shoddy branch, even that can at least severely wound a cat in one overhead swing, by crushing if not cutting. If a spear doesn't cut well through flesh it's probably a sledgehammer or some stuff. And judging by the pics:
The purple one is jagged as all hell, TEARING through flesh;
The serpenty spear is more for stabbing than for slashing;
The THREE bladed one okay you can figure it out yourself, stabbing by swinging;
The dragonswordy one is still deadly to cats without the fancy stuff;
The omega spear is likely heavy as forget, which equals more cutting force but horrible stabbing.
Are you even trying anymore?