This idea arose in the context of a discussion which generally addressed civility. The warnings would be civility warnings.
Fred
To that end, a warnings tool would be helpful, supplementing or replacing the uw- templates with a MediaWiki extension that requires that warnings be acknowledged by the editor to continue editing, and providing a record of warnings. This is basically a very soft block that the editor is free to remove themselves. Warnings need not be generally visible except in the case where a matter progresses to arbitration, but they should persist for a period of time so that patterns of behavior become apparent.
-Stephanie
Brilliant!
Fred Bauder