Technological flaming sword...

[Anthony]

Originally Posted by Johnny1A.2

I agree, it makes very little sense as a practical weapon. But I could I imagine a certain sort of person constructing one.

If your goal is showy and/or youtube videos, I'd probably go with a coating on a cheap sword (as none of these options are going to be terribly good for a sword). Not sure what you'd need to make a coating that both sticks and burns properly, something like a sparkler mix would probably work but might look silly.