@Jenkar
You could theorectically describe Elements with a bunch of qualities.
E.g.
Light : Reflection, Quality, Perfection
Darkness : Manipulation, Philosophy, Shadows
And why is alignments such a blantantly bad suggestion for this game? I was just trying to come up with a thematic explanation.
I'm kind of seeing the Slayer as a Knight-errant (
http://en.wikipedia.org/wiki/Knight-errant).
Such a knight might well be outside the structure of feudalism, wandering solely to perform noble exploits (and perhaps to find a lord to give his service to), but might also be in service to a king or lord, traveling either in pursuit of a specific duty that his overlord charged him with, or to put down evildoers in general.
In war stories and similar legends, Knights and lead warriors seem to have to a tendency to attack each other directly at some point rather than just staying behind and commanding everyone like most modern generals. This is also shown by the medieval sport of jousting where Knights tried to knock each other off their horses.