Talking bayonets, take a look at the SKS bayonet. It is triangular and damn near indestructible. I’ve used mine as a pry bar, digging stick and auger bit and it is still going hard.
Another advantage is they throw realy well – it isn’t hard to but them right through an internal house door.
[In saying this, i don’t advocate throwing your weapon away in a fight unless you are desperate for a moment of disorientation on your opponents part so you can disengage and run the hell away]
They can also be threaded on their base, making them relatively easy to mount as a pike if you have a tap and die set.