It would have to be a great big double heavy two handed ones. I'm useless with single handed swords... With two hands though, it could have two lightsabres pointing the same way next to each other, so it looks like a thick blade. Maybe even three, with the middle longer than the outer ones...
They'd have to be purple though. Any other colour looks over rated and colourful.
A Knight is sworn to Honour. His heart knows only Virtue. His blade defends the helpless. His might upholds the Weak. His word speaks only truth. His wrath undoes the Wicked.