I like Magnus's idea about a one-week period of 10 edits per day. It's less drastic than a complete ban, and it can serve as a sort of probationary period. The contributor could decide to "prove himself" and conform to our Courtesy and Neutrality policies during that period, hoping to get the quota lifted.
A little discipline won't hurt the project, but tolerating just a bit too much discourtesy will hurt it. Not everyone has the iron determination to plow through the muddy battle fields of edit wars and personal attacks.
(Maybe all those years of being teased for my last name "Poor Ed!" or my religion "You brainwashed zombie!" have strengthened my resolve, but even I thrive better in a congenial environment.)
Ed Poor, aka Unsolved Equation
P.S. I'm thinking of changing my ~~~ signature...