The character pictured in the article looks vaguely like Link if you've had a couple drinks. It might be important to note Nintendo's specificity to Wind Waker and not the Zelda series in general.

Character branding is simply a marketing manuvuer that is now becoming obsolete because with graphical community online games such as MMORPGs, people don't have to depend on the releases of a particular image of an alter-ego to live out their imagination. Say you see yourself as Wolverine or Link or Mario. The copyright holder of those characters has you as a loyal customer. If you're able to fashion your own image of an alter-ego, you break free of that grip and they lose their traditional business.

If Webzen is going to use the Linkish-looking character (who is wearing a blue Revolutionary War-style coat and NO HAT for those who haven't RTFA) as the primary advertisement for the game, then *maybe* Nintendo has some kind of point here. Otherwise, this is simply about owning the meta-image of a cartoonish character with spiky blond hair.

This would be like Disney suing Warner Brothers because Bugs Bunny kind of looks like Thumper.