Their should be a database of all last names that should not be accepted. Maybe their could be a string searcher, I agree. There are so many graphic novels that its hard to figure out which names are canon and which are not.
A side note, I thought that First names like Qui-Gon were ok according to the rules...
There actually is a listing of auto-blocked last names, like Skywalker. I'm not sure why Maul apparently did not make that list, nor Darklighter.
Keibak is correct; using the first name of a character is perfectly acceptable. Qui-Gon Mattia is therefore a valid handle.
William Lightsaber is questionable, but not explicitly restricted.. it isn't uncommon for last names to consist of an actual word, so that would be up to the opinion of whoever happens to handle such a request. Red Lightsaber would be another matter.