for the Knight of Life anon, something like the lich killing sword Caladbolg from Guild Wars 2 might work, since it is a giant thorn from a really, /really/, big tree

It would doubly work, you know why? Because Caladbolg is another name for Caledfwlch, which is, in turn, an equivalent to Excalibur.

What if all Knights have like.

An Excalibur-sounding weapon.